Bicycle Mechanics - rivet or screw (holds cable guide) won't let a new cartridge BB into BB shell

My housemate has a Schwinn Traveler from 1989 or so, and I just bought a new 113mm square-taper bottom bracket to replace his old (and completely shot) cup-and-cone BB. But it turns out that there's a rivet or a screw sticking down into the BB shell, that holds the cable guide onto the bottom (outside) of the BB shell, and this rivet or screw is too long and thus doesn't leave space for a sealed-cartridge BB to get into the frame.
What I'm wondering: is the cable guide held on by a rivet or a screw? I suspect it's a rivet, but can's see the head because I can't actually see the head of the thing. Here's pictures from the side, of the cable guide, and of the inside of the BB shell.
If it's a rivet, I could snap it (but then perhaps cable guide pops off, though I could glue it) or saw off the end. If it's a screw or bolt, then I guess I need to pull the cable guide off and use a shorter screw or bolt in the same place. I do have extra modern cable guide, and can glue or screw them on normally.
Here's pictures:
http://www.unc.edu/~cupery/pics/bike_parts/IMG_5993--bb_cable_guide_rivet.jpg
http://www.unc.edu/~cupery/pics/bike_parts/IMG_5994--bb_cable_guide.jpg
http://www.unc.edu/~cupery/pics/bike_parts/IMG_5990--bb_shell_rivet.jpg

Drill it out. Clean the bottom of the bracket cage, and glue the cable guide to the cage. Then install the new BB. Alternately, get a file and remove the inside burr.

The "rivet" in this case is simply a plastic stud with barbs, molded into the cable guide itself. If you can compress the barbs, you can remove the cable guide. If the hole is threaded, you can drill out the cable guide's stud and just use a short screw instead, or go buy a cable guide designed to use a screw. If the hole isn't threaded, you might want to just shorten up the stud enough to clear the BB cartridge, and see if it'll stay in place reliably with the shortened stud and no barbs.

Great. Thanks for the response.

I had this dilemma installing a Phil BB in a frame. I simply unscrewed the cable guide bolt/screw (so that it wasn't protruding into the BB shell), installed the BB loosely, then screwed bolt/screw all the way in and tightened down the BB. At first I thought I needed a shorter bolt/screw but the one supplied with the cable guide worked just fine.

Use a thin blade to cut the stud down to size. Its only there to hold the cable guide in place during the build of the bike. Cable tension holds the guide on after the bike is assembled.