The 135 Tele-Elmar (f/4) brings up the 24+35 frames on the M8. If you press in the lens lock release and turn the lens as far as it'll go, then you can get the 90 frames to show (thank Jaapv for that trick) and then guage the framing about halfway between that and the rangefinder rectangle. I have an off-brand zoom finder that actually has a 180mm setting which is what I use. Or you could buy a 135mm finder, which are easy to find, and mask it off. Or you could buy a 16464 short focusing mount and use the 135's lens head on a Visoflex III (I do that sometimes too).
As to the lens, there's nothing bad you can say about it. Using the aforementioned short mount, plus a 14167 M/Viso-to-Leica R mount, it can be used on any Leica reflex, and plus a Leica R-to-EOS adaptor can be used on any Canon EOS DSLR. I use mine on my 20D that way.