While the USART can go that fast at 4mhz, the closest to 115,200 you can get is 125,000, which is an 8.5% error.

If you use a 3.579mhz colorburst crystal. You can get 111,243 baud which is only 2.9% error.

Also there are a couple problems in your code. They may just be typo's, but...

The SERIALBYTE variable is missing. and...
just before JUMP: the "END IF" should be ENDIF.

HTH,