With a 4MHz crystal you might want to change to XT_OSC so you're not over-driving
your crystal.

I don't have an X3 board to test it with, but this definitely works on a breadboard with
a 16F88, and blinks RB4.
Code:
@ DEVICE PIC16F88, XT_OSC, MCLR_ON, WDT_OFF, LVP_OFF, PROTECT_OFF

ANSEL = 0
CMCON = 7

OUTPUT PORTB.4

blink:
  PORTB.4 = 1
  PAUSE 500
  PORTB.4 = 0
  PAUSE 500
  GOTO blink
  
  END