I assume you got this by installing sliderotate. Qwerty12's compilation/method is different. I believe the author of sliderotate said he was on vacation and could not recompile it for diablo at present. Search forums for this--perhaps there has been progress since I read the relevant thread a few days ago.

I also assume you're using an n800, since otherwise you'd be asking for the rotation-upon-keyboard-slide-out, instead of just when the power button is pressed. If so, while the power button is nice, sliderotate doesn't (I think) support rotation to the right. I find rotation to the right to be superior than to the left, since that leaves the d-pad near the thumb. But to each his/her own.