There's someplace out there that sells flat phone cord that's supposed to be able to be taped to a wall and painted over... I'm not sure how well it works, but for slow modem connections it would probably work fine... I don't know how your house is set up, but if you've got an attic or a crawl space underneath, would it be possible to run wires through there? Home depot has wiremold (or some other name for it) that's plastic conduit that you can hide wires in on their way up/down/around if you want to... Spend fifteen minutes looking at your house and try and find a way to get from one to the other, or back to the box. Wiring phones isn't hard, if that's what's slowing you down...

Matthew