It seems you do not read, or not read carefully.

Your PIC has USART.

USART has Interrupt that has nothing to do with PORTB.0 INT interrupt.

Darrels Interrupts cover all possible Interrupt sources of a PIC. You just have to enable th appropriate interrupt.

Example follows. On a terminal press key "1" to see the effect. (Not tested...)

Code:
INCLUDE "DT_INTS-14.bas"     ' Base Interrupt System
INCLUDE "ReEnterPBP.bas"     ' Include if using PBP interrupts

':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
	INT_Handler   RX_INT,	 _Get_char,	 PBP,  yes
endm
INT_CREATE               ; Creates the interrupt processor
ENDASM

':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::       

@ INT_ENABLE  RX_INT	   ; enable UART RX interrupt


loop:
if mybyte="1" then
    hserout "I got it!"
    mybyte=0
endif
goto loop


'---[USART RX Interrupt handler]----------------------------------------------------
Get_char:
	hserin 100,noreceived,[mybyte]	'Get byte
noreceived:                         'or if timeout return
@ INT_RETURN
Ioannis

P.S. As a homework do set the USART parameters with DEFINE's to 9600