atx/shift knobs

i saw in an older post these guys were cutting down their automatic shifter and putting shift knobs on etc... some were relocating the o/d button too...can someone give me details on this type of install (like how much do u cut, how to relocate o/d). one guy said he juss had a little round ball and a shift boot, thats what id like to do. and also, i dont want to lose the lil reverse lock out safety thing (where u cant accidentaly bump it into reverse when ur drivin), do u lose that with this mod???