I've seen a couple TF2 mods with Portal guns in TF2 maps and stuff like that. I tried playing a TF2 map through the console on Portal 2 but it crashed. Is there any way to edit a TF2 map and edit in Portal 2 features like the enter and exit doors to make it playable in Portal 2?

When you download source sdk, it comes with some decompiled tf2 maps that you can edit using the p2at and recompile for use in portal 2

Alright, sweet. I'm not familiar with p2at, what is that? (I'm just learning how to use Hammer)

Portal 2 authoring tools = hammer for portal 2.

I tried opening sdk_ctf_2fort in P2at. The first time I tried, it gave me a message saying the file was marked as read only. I changed that and now every time I try to open it, Hammer freezes up.