i switched from a shorter-throw projector to the HD1000U, which couldn't quite fill my 99" screen with a 11' deep room, but thanks to the non-zero lens offset i was able to ceiling mount it pointing backwards, get a 10" x 16" front-surface mirror (from www.highreflectivemirrors.com
, it was cheap), and bounce it. i mounted both as close to the wall/ceiling as possible to get the resulting image as high off the ground as i could. so what i did was this:
for the ceiling, i screwed a few slats up to the ceiling joists, then put 3 hanger bolts into those slats. cut a sheet of acrylic and drilled it (carefully... stuff cracks easily and i didn't have the special bits) with holes for the projector bolts and holes for the hanger bolts. put compression springs on the hanger bolts, slid the acrylic sheet (with projector attached) on, put wing nuts on the outside, adjusted to taste. oh yeah, a bunch of fender washers in there too.
for the wall, basically the exact same thing except i glued the mirrror to the acrylic and put the hanger bolts straight into drywall anchors instead.
results were excellent, it's very adjustable. the only thing i can't do is pivot or slide the projector side-to-side, so i had to get it well-centered to begin with, but i couldn't come up with a cheap way to build a mount that would do that, too, without pushing it at least a few inches down from the ceiling. as it is, it's quite close.