I'm not entirely sure why you'd want to play a roguelike on a gamepad, but I can see this being implemented if it isn't too difficult to code...
Oh, and the inventory menu of 0.9.9 RC1 is already hybrid, you can use the letter or use the arrows.
It would depend on how many buttons your gamepad has though.
D-Pad: Movement
Left trigger: Hold down to disable the D-Pad when only one direction is being pressed (So it's impossible to move non-diagonally while holding in L trigger)
Right trigger: Hold down for Shift (For special firing, special reloading)
Then you'd need buttons for: Fire, Reload, Get, Drop, Inventory, Swap Weapon, Go Down Stairs
So you'd need at the very least 7 other buttons...