It does bolt to the FWD transmission it's just that it's not very strong. The added power could likely tear it to pieces and break it very easily.
http://www.toyotacelicaonline.com/celica1/3sgteswap.htm The 1MZ 3.0L V6 5spd transmission bolts on, but you'd need the associated axles as well and maybe even have to switch spindles to make it work, I'm not too sure there.