So, one thing about Hexxit-like modpacks, there are a FUCK. load. of keys you need to map.
The pigfuck starts out with a million conflicting binds. I HIGHLY recommend going through and nuking everything and then going through it from the basics on branching out.
There are so many bindings for mods that I have never even used, and some of the others are for high end items anyway.
(The 1.2.0 build is right here: http://www.technicpack.net/modpack/hexx-reloaded-test-pack.655093 if you want to set it up in advance)
Once you are done, BACK YOUR SHIT UP!!!
C:UsersyourmomAppDataRoaming.technicmodpackshexx-reloaded-test-pack
(If you go to the menu in game and click Resource Packs -> Open Folder, that works too)
There, then back up options.txt.
Recommended order/proximity efficient key priority (in your controls menu):
1. Movement (I don't use defaults)
2. Gameplay
3. Inventory
4. Inventory Tweaks
5. Backpacks (There are multiple backpack mods, keep that in mind)
6. Miscellaneous -> The first five and second to last options are controls for Witchery... which is a fucking KICK ASS MOD, and I highly recommend checking it out (it's a bit of a bitch to get figured out)... but if you don't use it yet/plan on using it at all, you can leave these keys unmapped.
7. Multiplayer
Everything else is dealer's choice, but I do recommend making sure you have your shit mapped for Zelda sword skills since they work with every sword, and Traveler's Gear is helpful stuff that can be made pretty early or found in medium+ loot chests.