Cable Liner under Bottom Bracket

The recovered Roubaix meth-mobile has internal cables and hoses (that were miserable to fish around in the frame), but it has an open window under the bottom of the bottom bracket where the cables are exposed but run through inner-liner. the ends of the inner liner are inside the frame or run up the front derailleur cable.

The cables on my commuter run externally and stick a lot on the BB cable guide, and I was wondering if anyone has tried putting those through a run of inner liner. I suspect they might fill up with water, but they might also keep the cables from sticking.

-- Jay Beattie.