just regular ole clear silicone 4.50 at wally-world. it drys in like 15 minutes to half an hour and is a sealer/adheisive. Look around Office Max an the like they carrie a product that we use to cover power cords and phone cords running up the walls. It looks like a hollow square tube but its two peices that snap together and have an adheisive backing. You can cut it to any length and to even turn corners. Seal the flex watt in the bottom and run that up the wall on the inside to hide the cords.

Like this http://www.cabletiesandmore.com/raceways.html

Just my two cents