I don't mean to sound snippy, but do you have a PICBASIC PRO manual? You can view it on line if not. You have several options, the syntax is easy for your application.

1). write inline assembly in the middle of PicBasic for the tx routine
2). use a for loop to toggle through your tx routine X-number of times (number of cycles) using the pauseus running at > 10Mhz clock.
3). write it all in assembly and run whatever clock frequency you want.

Best Regards,
Nick