As CocaColaKid said... 18F's MUST use the MPASM Assembler.

Here is an EXAMPLE (for PIC18F2420) of the instructions that can be included at the start of your PBP program...

Code:
	'
	'	PIC Defines for PIC18F2420
	'	==========================

	@ __CONFIG    _CONFIG1H, _IESO_OFF_1H & _FCMEN_OFF_1H & _OSC_INTIO67_1H
			' Oscillator Switch-over Disabled
			' Fail-Safe clock Monitor Disabled
			' _OSC_INTIO67_1H Set for Internal Oscillator RA6 & RA7 Enabled
	@ __CONFIG    _CONFIG2L, _BOREN_ON_2L & _PWRT_ON_2L & _BORV_0_2L
			' Brown-Out Reset Enabled
			' Power-On Timer Enabled
			' Brown-Out Trip set to 4.2v
        @ __CONFIG    _CONFIG2H, _WDT_ON_2H & _WDTPS_128_2H
			' WatchDog is ON
			' Watchdog Postscaler set to 1:128
	@ __CONFIG    _CONFIG3H, _MCLRE_OFF_3H & _PBADEN_OFF_3H & _CCP2MX_PORTC_3H
			' MCLR is OFF (internal)
			' PortB 4:0 is digital on Reset
			' CCP2 is Multiplexed with PortC.1
        @ __CONFIG    _CONFIG4L, _STVREN_ON_4L & _XINST_OFF_4L & _LVP_OFF_4L & _DEBUG_OFF_4L
			' Stack Under/Overflow will Reset System
			' Enhanced CPU Addressing Disabled
			' Low-Voltage Programming is OFF
			' DEBUG is Disabled
	@ __CONFIG    _CONFIG5L, _CP1_ON_5L & _CP0_ON_5L
			' All Code Protect
        @ __CONFIG    _CONFIG5H, _CPB_ON_5H & _CPD_ON_5H
			' EEPROM is Code Protected
			' Boot Block code is Code Protected
Here is an extract from the P18F2420.INC file in the MPLAB MPASM Suite subdirectory... note how (1) The ones needed have been copied from the INC file and inserted into the CONFIG statement.... and (2) for detailed explaination of each feature, refer to the DATASHEET - but I mustn't say that because I'll get flamed, so instead direct your queries to various members of the forum who'll read the Datasheet for you...

Code:
;----- CONFIG1H Options --------------------------------------------------
_OSC_LP_1H           EQU  H'F0'    ; LP oscillator
_OSC_XT_1H           EQU  H'F1'    ; XT oscillator
_OSC_HS_1H           EQU  H'F2'    ; HS oscillator
_OSC_RC_1H           EQU  H'F3'    ; External RC oscillator, CLKO function on RA6
_OSC_EC_1H           EQU  H'F4'    ; EC oscillator, CLKO function on RA6
_OSC_ECIO6_1H        EQU  H'F5'    ; EC oscillator, port function on RA6
_OSC_HSPLL_1H        EQU  H'F6'    ; HS oscillator, PLL enabled (Clock Frequency = 4 x FOSC1)
_OSC_RCIO6_1H        EQU  H'F7'    ; External RC oscillator, port function on RA6
_OSC_INTIO67_1H      EQU  H'F8'    ; Internal oscillator block, port function on RA6 and RA7
_OSC_INTIO7_1H       EQU  H'F9'    ; Internal oscillator block, CLKO function on RA6, port function on RA7

_FCMEN_OFF_1H        EQU  H'BF'    ; Fail-Safe Clock Monitor disabled
_FCMEN_ON_1H         EQU  H'FF'    ; Fail-Safe Clock Monitor enabled

_IESO_OFF_1H         EQU  H'7F'    ; Oscillator Switchover mode disabled
_IESO_ON_1H          EQU  H'FF'    ; Oscillator Switchover mode enabled

;----- CONFIG2L Options --------------------------------------------------
_PWRT_ON_2L          EQU  H'FE'    ; PWRT enabled
_PWRT_OFF_2L         EQU  H'FF'    ; PWRT disabled

_BOREN_OFF_2L        EQU  H'F9'    ; Brown-out Reset disabled in hardware and software
_BOREN_ON_2L         EQU  H'FB'    ; Brown-out Reset enabled and controlled by software (SBOREN is enabled)
_BOREN_NOSLP_2L      EQU  H'FD'    ; Brown-out Reset enabled in hardware only and disabled in Sleep mode (SBOREN is disabled)
_BOREN_SBORDIS_2L    EQU  H'FF'    ; Brown-out Reset enabled in hardware only (SBOREN is disabled)

_BORV_0_2L           EQU  H'E7'    ; Maximum setting
_BORV_1_2L           EQU  H'EF'    ; 
_BORV_2_2L           EQU  H'F7'    ; 
_BORV_3_2L           EQU  H'FF'    ; Minimum setting

;----- CONFIG2H Options --------------------------------------------------
_WDT_OFF_2H          EQU  H'FE'    ; WDT disabled (control is placed on the SWDTEN bit)
_WDT_ON_2H           EQU  H'FF'    ; WDT enabled

_WDTPS_1_2H          EQU  H'E1'    ; 1:1
_WDTPS_2_2H          EQU  H'E3'    ; 1:2
_WDTPS_4_2H          EQU  H'E5'    ; 1:4
_WDTPS_8_2H          EQU  H'E7'    ; 1:8
_WDTPS_16_2H         EQU  H'E9'    ; 1:16
_WDTPS_32_2H         EQU  H'EB'    ; 1:32
_WDTPS_64_2H         EQU  H'ED'    ; 1:64
_WDTPS_128_2H        EQU  H'EF'    ; 1:128
_WDTPS_256_2H        EQU  H'F1'    ; 1:256
_WDTPS_512_2H        EQU  H'F3'    ; 1:512
_WDTPS_1024_2H       EQU  H'F5'    ; 1:1024
_WDTPS_2048_2H       EQU  H'F7'    ; 1:2048
_WDTPS_4096_2H       EQU  H'F9'    ; 1:4096
_WDTPS_8192_2H       EQU  H'FB'    ; 1:8192
_WDTPS_16384_2H      EQU  H'FD'    ; 1:16384
_WDTPS_32768_2H      EQU  H'FF'    ; 1:32768

;----- CONFIG3H Options --------------------------------------------------
etc etc etc
You will need to modify the 18F2420.INC file located in your PBP directory to something like this... (remembering to backup the original)...
Code:
;****************************************************************
;*  18F2420.INC                                                 *
;*                                                              *
;*  By        : Leonard Zerman, Jeff Schmoyer                   *
;*  Notice    : Copyright (c) 2004 microEngineering Labs, Inc.  *
;*              All Rights Reserved                             *
;*  Date      : 12/31/04                                        *
;*  Version   : 2.46                                            *
;*  Notes     : Butchered by Melanie                            *
;****************************************************************
        NOLIST
    ifdef PM_USED
        LIST
        "Error: PM does not support this device.  Use MPASM."
        NOLIST
    else
        LIST
        LIST p = 18F2420, r = dec, w = -311, f = inhx32
        INCLUDE "P18F2420.INC"   ; MPASM  Header

        NOLIST
    endif
        LIST
EEPROM_START	EQU	0F00000h
BLOCK_SIZE	EQU	8
This is because the MPASM Assembler cannot handle CONFIG conflicts....

Finally, to make it all compile (and remembering to ensure you have a PATH embedded pointing to your MPASM directory), you can compile with a command line like...

PBPW -p18F2420 MyProgram -ampasmwin -v

Hey presto... it'll compile and embed all your selected CONFIG directives into the resultant HEX file (and as a bonus MPASM displays a lovely green progress bar that just makes you feel all warm and fuzzy inside).

You may get some warning messages (they're just Warnings and NOT Errors) from MPASM that the CONFIG statements have been depricated, but a search on this forum will reveal how to suppress those.