TiCycles in Portland, OR routinely S & S couples bikes. both new and existing, He does it for several high end frame builders, both steel and ti. They send the complete frame, TiCycles cuts and couples them and sends them back. Two of the ti builders they couple for are considered among the very best, so I don't think that andr0id's concerns (posted above) should bother you.
I am a regular visitor at the TiCycles shop and get to drool over some of the frames they get to saw apart!
Edit: call TiCycles. They can probably tell you over the phone if they can couple your oval tubes.
Ben