Hey Steamer,
Im having a similar issue right now too, and I have a lot of wires to deal with (clutch, f. brake, r. brake, rear derailler, throttle, speedo). What ive realized is that there is no way to hide them all in the frame as you said, so I figured im gonna just try to clean it up as much as possible. I Decided to run my throt., clutch, rear brake and derailler underneath my lower main tube, and I figured that if you put the cables side by side (as opposed to clumped together), you can geth them flat enough agaiunst the bottom of the tube that they are not very noticeable, however my lower main tube is very wide so that helps. I also tape all of the cable runs with black Hockey Tape (my bike is semi gloss black) instead of electrical tape, as it is not shiny like electrical tape, and also lends itself to more of and ol' school cloth wire look. Thats how I tackled it.....so far
With your idea of color matching the tape to your bike, if you layed the wires side by side and taped them the same color as the frame, you wouldnt notice them at all. Have you figured out any ways to tidy up the cables around the handlebar area though? Thats where im having the most dificulty as Ya cant bend the cables too sharp to tuck them in so my bar area still looks messy...... Any other ideas would always be appreciated!
-Dan