I haven't seen any undetected wall hacks for mw2 steam 1.2.208 but there is a brilliant esp and aimbot hack, also there is a never detectable aimbot that uses pixels for mw3 but you can use that for mw2 so he are the link.
Esp and aimbot aimbot: http://www.mpgh.net/forum/269-call-d...ml#post6812946
Pixel aimbot hack: http://www.mpgh.net/forum/404-call-d...or-aimbot.html
If you use the pixel hack install this as well helps a lot while using it, http://www.mpgh.net/forum/191-call-d...-versions.html
I posted these because could't find any good wallhacks so just use the esp and aimbot because you can see enemies through walls because there is a red box around all enemy players so there.
Hope this helped.