I just did a quick search, and you're not the only one who's asked that question. The answers others got tend to lean towards tuning and checking the engine to make sure it's all up to snuff first, like valve adjustments and making sure the decompression system is working as it should.
You probably just have to figure out which variant of the FB460V had electric start, and go from there. Just a quick look at Kawasaki's small engine site, searching parts for the FB460V, the FB460V-S32 shows electric starter parts. Didn't look to see which other ones might have.
Here's a "race" version on a John Deere STX38.
http://www.youtube.com/watch?v=riW_7T7YY2w
Googling John Deere Kawasaki FB460V it looks like the 160, 165 series of lawn tractors, and maybe others had that engine, and were most likely electric start.
Snapper came up with the FB460V on walk behinds and riders too.
I've done it to a couple of much smaller engines, so to warn you, the cost to make the conversion might make your head spin when you get to adding it all up. Besides the starter motor, you might have to change out the flywheel, then there's all the electrical wiring and connections that are probably different, like charging coils, rectifiers and such.
Might check with Kawasaki to see what they recommend, and get a hold of a John Deere and Snapper dealers. Maybe they could give you some pointers too, and you might be able to locate the stuff you need from something being parted out like I did with the engines I converted.
Good luck with your conversion.