properly UV unwrapping "edge loop" geometry? Think of a geometry like this (blend attached):



Now imagine you have a texture image such as this, which you want to have tiled horizontally on that selected surface (polygons).



To get a result akin to this:



How can you do that without starting from scrach?



PS. Cylinder unwrapping only works to a degree, the texture gets noticeably stretched at places compared to other places.
First remove doubles (W-->Remove Doubles) and apply transformations (Ctrl+A-->Apply Rotation, Scale). Then hide the non selected part of your mesh with Shift+H. Mark seams (select edges as pictured below and press Ctrl+E-->Mark Seam). Then select it with A and unwrap it U-->Unwrap.


Now straighten the UV islands ( How do I straighten UV maps? ).