The stuff you are looking for is Kasenite. You may be able to get it from the local Acklands Grainger, or similar supply outfit, or from a welding supplies place. You can get a pretty decent case with it, if you follow the directions and repeat a time or two or three. Red hot and dipped in oil works well if the steel has enough carbon in it to harden it that way, Kasenit puts carbon into the surface, so it will harden when quenched, if the steel does not contain enough. Using Kasenite on high or medium carbon steel is asking for issues, like cracks and brittle parts. Chances are really low that they would have case hardened a high or medium carbon steel though. If they are case hardened, then Kasenite is the way to go. Poor boy/ old school version is to pack it into an airtight box crammed full of charred leather, cow hooves, etc, as a source of carbon, and cooking it all at red heat for an hour or three. You can either dump it directly from the container, into the quench medium, or allow it to cool slowly, file and adjust as required, then heat to red, and quench to harden the surface.
I learned how to strip and re-assemble a trigger on a C7 without any help except knowing that I had not lost any parts, and that it had passed the function tests before I started. I'd recommend that method to a newbie. It ain't rocket science, and it's not like telling them to go ahead and file off the locking lugs, or something as foolish as that.
It'd soon enough sort out whether he should be mucking about inside a gun, or paying someone else to.
Different strokes though.
Re: the comments on the SIG. The triggers on the Sharps ain't that. Probably why they didn't send a DVD along. As per mooncoon's suggestion, the triggers have a lot more in common with an old school muzzle loader trigger and lock, than with your Sig. Minimum number of moving parts, between the triggers and the locks.
Now, I still stand by the idea that if you NEED to ask, you shouldn't be muckin' with it. Wanting to ask, that's a different kettle o' fish, innit?
Cheers
Trev