Any how I had to rebuild some cabnets in my old TT. That said, the cabnets were held together with wavy strips if metal pressed in to the pressboard wood, I was able to dig into the pressboard and pull the strips out.
When reassembling the cabnet I used a cheap "biscuit" cutter I bought from Harbor Freight. The biscuit cutter cuts a slot into the two pieces of wood and a small wooden "biscuit" is glued in holding the two pieces of wood together.
The project came out looking great.
Good luck! and post the photos.
2005 F150 XLT Supercab LB Heavy Payload 5.4, 4.10
2007 Jayco Jayflight 31BHDS
Back-up camera on the TT with infrared & microphone
Reese duel cam hitch, U-bolt style ($40 at a garage sale)
2 canoes, 3 kayaks, & camping dog (Tootsie)
Mine was easier since the trailer was a gut job and I was building new cabinets.
Depending on what you need to cut you may need a variety of tools. For front cabinet surface you could plunge cut using a small battery powered circular saw.
Alternately a variable speed jig saw may work or even one of those "multi" cut saws in which the blade simply vibrates.
For other hard to reach places in the back you may need to use a sawzall.
For keeping mine in place I reused the door hinge bolt holes on the top. On the side of the door hinges I had to dig around for some longer screws but it worked perfect!. Be aware that in my case the screws are metric size.
Depending on the fridge you do not want to screw into the sides or top of the fridge since often times they run coils on the sides and top of the fridge. If you don't have coils on the back of the fridge it is a sure bet that they will be in the sides and top.
Some fridges also run either electric heater or tubing around the door openings to reduce sweating so be careful about drilling or screwing in those areas.
For a fridge latch, I found a small latch at my local hardware stor which fit in between the fridge and freezer door then simply put a sheet meta screw in the bottom of the freezer door and the top of the fridge door. When traveling I move the latch to cover the screws and when parked the latch is pulled back away from the screws.
For other great ideas (and pictures of someone else's conversion)you can check HERE (it is a different RV website).