have a look there
http://www.picbasic.co.uk/forum/showthread.php?t=543

you can't change toa 36MHZ crystal... it will be over the PIC spec (as far as i remind) BUT you'll be able to run your PIC @36MHZ by using the internal PLL (wich multiply your crystal frequency by 4)

In your case 36/4=9MHZ... if it exist

BUT PBP don't allow 36MHZ... well yes but not directly. You'll have to play with the timing. Why not running it @40MHZ? PBP support this frewuency and you'll need a 10MHZ crystal.

HTH