The way I have done this...because trying to draw lines in PS is a pain is this....UV the top and bottom of the seat as seperate pieces. THEN whilst in the UV editor...pick all of the blue face and cut the UV's...then just move them to one side and presto...easy as in PS then! No trying to draw lines.....hope this helps.

cheers bullet

EDIT: select the faces in perspective...sorry mate...then cut and move