Depends.... What's you oscillator speed? At 20Mhz an instruction cycles is 200ns so, in theory, doing something like
Code:
PauseUs 536
@ NOP
@ NOP
should get you pretty close (536.4us). If the timing is that critical then it's probably not going to work the way I wrote it since there will be "gaps" between the preamble, command, postamble etc. You'd need to build the complete message in a larger array and then send it but that gets a bit complicated due to the variation in length of the commands (they won't line up at even byte boundries).

/Henrik.