Get a good antenna and pray to the scanner gods.
Seriously, the system is a tough one to monitor, but if you can get a good signal you'll be OK.
I assume you know the frequencies and talkgroups to program in? If not, the RRDB listing is very complete for Mesa. You'll find them listed in the Phoenix PRWN system. Don't bother to program in the talkgroups that are marked as encrypted in the RRDB - They are truly encrypted!
You'll want to program Gilbert in also, they share the system and often assist mesa units, and vice versa.
Good luck... you're gonna need it.
-AZ