first off you would need to shoot against a green screen and then chroma key the footage. it could be done with the keyer in fcp but probably not with good results , fcp dosent have the greatest keyer. i would look into dv matte pro which is a plugin for fcp and after effects , its one of the best keyers out there for mini dv and its cheap ,somewhere around $150 at dvgarage.com this might be of some help, to you http://www.wwug.com/cgi-bin/viewarticle.cgi?id=31381
You can also shoot white (minimize shadows) and pull a lumikey off of it or crush the levels.
If you want the white ipod, earphones and wires you'll need to rotoscope it (trace it in an effects package)
