Yep, the old fuel tubing has a 1000 and 1 uses
Here's a how-to, cut and pasted from a previous post:

"Fuel tube O rings are easy. Remove the LSN and HSN needles and cut off the crappy dry brown factory O rings. Now cut a piece of fuel tubing a little wider than the O ring groove on the needles. Open the tubing using the end of a pair of needle nose pliers and slip it over the screw driver slot end of the needle. Fit the leading edge into the O ring groove and leave the tail end sitting out of the groove. Now screw the needles in to their seats and the excess fuel tubing will be neatly cut off as it passes the end of the needle housings. Unscrew needles again and remove any excess tubing material. Refit the needles and your done."