Your timing must be syncronized, and I don't see this in your code...

You are using modified hobby (futaba, hitec, alpex,etc) servos for continuous rotation, right?

You have already calibrated them? To calibrate send pulses of 1.5 ms and actuate on the reference potentiometer until de servo stops. After your servo is calibrated you can use the forward and backward comands.

Do you have 3 conditions:

forward: 1.0 ms
stopped: 1.5 ms
backward: 2.0 ms

so do you have up to 2.0 ms to define movement and 18ms of pause between pulses

//eg. routine
// forward
set bit p3.3
set bit p3.4
call halfmilisec_delay
set bit p3.3
set bit p3.4
call halfmilisec_delay
set bit p3.3
set bit p3.4
call halfmilisec_delay
clear bit p3.3
set bit p3.4
call halfmilisec_delay
clear bit p3.3
clear bit p3.4
call 18milisec_delay

// stopped
set bit p3.3
set bit p3.4
call halfmilisec_delay
set bit p3.3
set bit p3.4
call halfmilisec_delay
set bit p3.3
set bit p3.4
call halfmilisec_delay
clear bit p3.3
clear bit p3.4
call halfmilisec_delay
clear bit p3.3
clear bit p3.4
call 18milisec_delay

// backward
set bit p3.3
set bit p3.4
call halfmilisec_delay
set bit p3.3
set bit p3.4
call halfmilisec_delay
set bit p3.3
set bit p3.4
call halfmilisec_delay
set bit p3.3
clear bit p3.4
call halfmilisec_delay
clear bit p3.3
clear bit p3.4
call 18milisec_delay