Here is what I have used in the past:
' WRITTEN BY DAVID PUROLA 09/18/2012
'
' WRITTEN FOR USE W/18F26K22 E/P @ 64 Mhz.
'
DEFINE OSC 64

#CONFIG
;----- CONFIG1H Options --------------------------------------------------
__config _CONFIG1H, _FOSC_INTIO7_1H & _PLLCFG_ON_1H & _PRICLKEN_ON_1H & _FCMEN_ON_1H & _IESO_OFF_1H
;----- CONFIG2L Options --------------------------------------------------
__config _CONFIG2L, _PWRTEN_ON_2L & _BOREN_ON_2L & _BORV_190_2L
;----- CONFIG2H Options --------------------------------------------------
__config _CONFIG2H, _WDTEN_OFF_2H & _WDTPS_32768_2H
;----- CONFIG3H Options --------------------------------------------------
__config _CONFIG3H, _CCP2MX_PORTB3_3H & _PBADEN_OFF_3H & _HFOFST_OFF_3H & _T3CMX_PORTB5_3H & _MCLRE_EXTMCLR_3H
;----- CONFIG4L Options --------------------------------------------------
__config _CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _XINST_OFF_4L & _DEBUG_OFF_4L
#ENDCONFIG

OSCCON = %01111000 'ENTER SLEEP MODE ON SLEEP,16 MHZ,FODC<3:0>
OSCTUNE = %01000000 'ENABLE PLL FOR 8 OR 16 MHZ.
OSCCON2 = %00000000