the reason not all camera's can be used in a trail cam is for several reasons. here are just a few.

the picture quality is poor, takes the camera too long to power up and take a picture (i.e. the sony powers up and takes a picture in around 2.5-3 seconds, that is from the time the sensor has been triggered). if the camera takes too long to power up and snap a pict then you would miss a lot of animals walking by. the flashes on them may be poor. a lot of them are too complicated to hack into. the p32 is very easy, I can have one ready for a unit in about 10 minutes. those are the main ones though I could think of off the top of my head.

with all the supplies and instructions provided at hagshouse, I believe anyone could build one with a little patience. The first one will take you around one day to complete, the rest go faster.