Well, maybe it's just my eyes, I don't know.

WRT overlay controls -- maybe possible, but very difficult and quite time-consuming, I'd guess.

But anyways, hjkl-mode keyboard controls work just fine, seeing as they've been specifically designed for limited and cramped keyboards like the N900's.

(Use h,j,k,l for moving in the cardinal directions, and y,u,b,n for the diagonals. Works quite nice, especially for the non-english keyboard models without proper arrow keys.)