I'm a day late and a buck short, but there's a writeup on how to modify the PST settings located at
http://cricketmafia.freeforums.org/viewtopic.php?t=4
(You need to register to see the topic)
you can ignore everything except section 4, thanks to all the folks who contributed to the kitchen ROM's and building the cricket extrom into it.
You're on your own when it comes to changing the MSL, but luv2chill already hooked you up on that one.
For future reference, I'd recommend buying verizon or alltel phones if you're modding them to work on cricket.