I once found an Xpadder profile for the game, although I do not recommend it. Put it simply, there are too many keys you use in your keyboard to emulate it in the gamepad. You can move, fire/attack, open the inventory, scroll through your disciplines, jump and open the character sheet, but you'll lack the necessary buttons to feed, reload, crouch, toggle first/third person view mode and the number keys to choose dialog options and quick choose disciplines and weapons.
That was my experience with my Xbox 360 controller for Windows and Xpadder, a software that emulates keyboard and mouse on your gamepad. Version 5.3 is free and the website is here: http://www.xpadder.com , although I could not find the download link exactly. --- I am always wrong in this website, and I only notice it because someone always says "read further down" to me.
There are some FPSs for consoles that use the analog sticks, and those work really well. Unfortunately, that cannot be said if you emulate your mouse in an analog stick. --- I am always wrong in this website, and I only notice it because someone always says "read further down" to me.