aup mate i've done this afew times now, it was a right bastid to start
sure its a torx 35 you need make sure it's a tight fit

that way you wont round it off, use a rachet but put something on the end to protect your window(few wraps of tape should do it) i dint do that to start with an it chipped my window when the rachet came off

it is well screwed in, it was on mine,
when you move the seats out the way you got a screw on the back panel, undo it remove panel, taking the bulb holder out is easy, just twist it.
change ya bulb,
now comes the good bit,
when you try to get it back in you cant, there's a rubber seal in the way(pain in the arse

)
get some long nose pliers if the wing nuts tight, loosen em about half way, enough to get the bulb holder back in (don't take the nuts right off there bastids to get back on).
screw it all back together make sure you got a good seal on your light, an put the rest of the ****e back together in reverse order
oh an good luck mate
nick