thanks mateI can only reply with what everyone else has said, I am seriously impressed. I also want to try and help though. I use AutoHotKey now and then so have knocked up this really small script.
Download autohotkey from here: http://www.autohotkey.com/download/
Copy the code from here: http://www.paste.to/NzczNQ==
Put it in a file called "Deadspace2Remap.ahk" - location is unimportant but it needs to be .ahk.
Here's my small script to rebind R Mouse to w but I have also included example code so you can see what else is possible. The symbol ";" at the start of the line means comment - ie AutoHotKey ignores anything on the line with ; at the start as it's a comment about the code. Feel free to adjust as you like.
To run an autohotkey script you double click the .ahk file. This will run until you stop it (check the system tray for the icon and r click - but as I switched this to W it might be easier to shutdown the process called autohotkey.exe which will do the same thing).
Bonus edit: If you can re-map the keys that don't usually remap on your mouse to something autohotkey can "watch" it might be possible to double remap eg: remap in your mouse software usualbutton1 to Mouse4 then remap in AHK Mouse4 to X
i will give this a try...