How about leaving the frame alone and making certain that it's locked up properly? I doubt a thief in doodooville will attempt to take it if he has to go thru 2 locks. (make sure they are 2 good locks).
As far as parts...see numerous other threads on subject - example, chain thru seat, solder in allen bolts, etc...
A thief that knows bikes will be able to see thru the disguise.