the default key settings are evil, of course.
i've found that they can be configured in the key_config.txt file.
it seems that the key names are not documented anywhere, so i'll write them here for anybody who gives a fart.
alphanumeric keys 0..9 and a..z are written just with the corresponding char; the other keys are:
fkey* (where * goes from 1 to 15),
backspace tab enter scrolllock capslock numlock space printscreen pause
leftshift rightshift leftcontrol leftwindows leftoption leftalt rightalt rightoption rightwindows rightcontrol
insert home pageup delete end pagedown
uparrow leftarrow downarrow rightarrow
divide multiply substract add decimal
numpadequals numpadenter numpad* (where * goes from 0 to 9)
backslash semicolon period apostrophe slash leftbracket rightbracket comma
mousebutton1 mousebutton2 mousebutton3 mousebutton4 mousexaxis mouseyaxis
note that some in-game key combos don't work with any arbitrary setting you may like.
iirc, i had problems using shift when doing the jump-flip (or whatever that maneuver is called :p)