I would bet you're right about having to disconnect hoses, but don't know for sure by just looking at an image on Google. If you do have to disconnect the A/C hose, you should take it to a shop which will be able to completely remove all of the refrigerant from the system prior to opening it up. After you get the hose off, you'll need to get a new drier to replace the old one: once exposed to atmosphere they're on the way out. Once you get everything back together, you can take it back to the shop which purged your system and have them refill for you, as it should be discounted (but not free).
NOTE: The reason you'd want to have them empty the system is that if you break the lines and the refrigerant dumps out, you can get freeze-burns from it. Not a good thing to have a digit get frozen ...
I'm just curious why you don't just try to fix the old one? Is it that far gone? Is it too busted up where you can't use some fiberglass/resin to reinforce what's good? It's amazing what you can do with the stuff.
As far as pitfalls, I wouldn't think you'd run into any trouble besides keeping track of parts when you pull it all apart. The link you posted in the comments looks like a disaster! Just keep everything tidy and in order and you shouldn't have any issues.