I use gore cables and have no issue with them after being careful with installation. I'm struggling to see how full outers differ from sealed cables in terms of keeping much out. Both have a continuous covering from shifter to mech. Using sealed cables would save any frame drilling but offer the same protection to the cables. I'm intentionally avoiding comments about compression of housing and shift crispness.
However, in answer to the OP, I don't think there is a pretty way to hook full outers onto a stopped frame. Your choices are.
Stick on hose guides
clamp on hose guides (through the cable stops)
A Dremmel
Wrap O rings around the frame and feed the housing through
see a frame builder
fit sealed cables.
Zip tie to an existing hose