Attached Link: http://www.richardrosenman.com/software/downloads/

Or try using a cylinder for your star field mapping (obviously this will depend on your camera angles) - just take a cylinder into the Modelling room and convert it to the Vertex modeller. Delete the top and bottom parts of the cylinder so you are left with the tube.

Regarding texture stretching in spherical mapping if you've got Photoshop click on the link, scroll down and look for the Spherical Mapping Corrector plug in. That ought to sort that out.