You should just skip the backlight switch all together, really. It's rather pointless since the reflective foil is removed for the backlight.
OOOOHH!!!!! if you just want to go between the half and variable speed, you want a dpdt switch =] if you want regular, half, and variable, you could use this http://search.digikey.com/scripts/DkSea =EG2413-ND =]
a dp3t switch. if you use a on-off-on switch, make regualr the middle (off) and dont desolder the regular crystal from the board, or else it wont work. if you use an on-on-on switch, you can desolder it and put it on any paired poles =]
OOOOHH!!!!! if you just want to go between the half and variable speed, you want a dpdt switch =]
SPDT
DPDT is overkill for just on-on.