Bob-
I had an old Centerline modular wheel start leaking from the joint a few years ago and I fixed it easily without taking the wheel apart. The wheel halves were riveted, not bolted, so taking them apart was impossible. All I did was dismount the tire, cut the silicone bead between the two halves out with a razor knife, wire brush the joint clean of any residue, wipe it down with acetone, and laid a new bead of silicone in.
The air pressure in the tire tends to push the bead into the joint when it is inflated, I think, so it doesn't seem to be critical to actually get the sealant in the flange and around the bolt heads, although that would probably be ideal.
The wheel I repaired worked fine for several years after that. I don't know how it held up long-term, since I sold the car to a guy in Australia.
TT