Therian,
Well, let's see:
Code:
Start:
  PortB.1 = 1     'Set pin high        
@ NOP             'Wait....Two NOP's are neede if we want 50% dutycycle
@ NOP             'since the GOTO takes two instruction cylcles.
  PortB.1 = 0     'Set pin low
Goto Start        'Do it again. The GOTO takes the same time as two NOP's
This, I think, will generate a pulsetrain with 50% duty cycle. The frequency would be ~833kHz. Not much of a radio frequency.... besides that, you can't do anything else in the code without slowing it down more...much more.

/Henrik Olsson.