I'd use it, just cut it off where you want it. Be sure to hand-sew a bar tack over the teeth so you don't slide the pull off the zipper. I always use a 9" zipper on pants & cut off the excess. A lot easier than trying to get it around a corner.

Be sure you cut the top of the zipper not the bottom :) Good luck.

Thanks so much jomuir, but am I not thinking right? wouldn't the TOP of the zipper be where the pull is when the zipper is closed? I thought it would be the other end you would cut off. Sorry to be so thick headed but I must be thinking wrong. thanks again.

Jomuir is right. The top where the pull is when closed is the end that needs to be cut off.
The zipper should be one inch smaller. If this is a nylon zip, you can sew over it with a machine. Try to keep the top edge lined up, then sew back and forth at least 4 times. THEN cut off the excess, leaving about a half inch. Sew first, then cut, in case it didn't come out right. This way you can take out the stitching and try again.
The stitching line will then act as a stop.

I so understand the thinking. I still tend to do it backwards with standard zippers. It finaly clicked when I first used the make your own zippers (which oddly enough you are making the stops on both ends)

With a premade zipper you have a perfect end stop to prevent the zipper head from sliding into a seam or worse. Since this is the more difficult one to self-make USE IT. The zipper pull stop at the top is simply made by putting enough stitches over the teeth to stop the pull from pulling off the zipper. With poly zippers a zigzag at the proper place usually works. You can then chop excess off or just cut the teeth off the tape if you have the tape sticted into your project.

This are a couple of links to helpful tips for working with continuous (make your own) zippers. The first does a decent explanation of tab stops and when they might not be necessary.

http://www.questoutfitters.com/zipper_tips.htm
http://www.marymulari.com/tips/zippers/

I always did it the other way....I'd put the tac stitches at the bottom of the zipper where I wanted the shuttle to stop when the zipper was open...then cut off about 3/4 of an inch below that. That way at the top the tab with no teeth that you want to sew onto the end was still available to use....and I tacked it well enough that it would stop for sure.

I do it from the bottom also. You only need to make one tack that way, but if you cut off the top, you need to make a tack on each side. Plus, the bottom of a zipper is usually the end that is not visible so I think it looks better.

I always cut off the bottom, too, whether for pillows or in garments, because it never shows. Of course, you do cut off the tops of separating zippers if you have to shorten, but the cut off tops are usually then encased in a hood or collar.

Why is cutting off the top of a skirt zipper better than cutting off the bottom?

I don't know where my other post went to so I hope this isn't a replay. I noticed on one of the zippers I had that they showed shortening it by cutting off the bottom of the zipper, (why didn't I see this before?) so now I know apparently either one will work just fine. So, thanks so much for all your input. I will not forget this info. Thank goodness for gardenweb. What would I do without it?

Professional seamstress here, and I always shorten from the bottom. Boss does, too.

Right! From the top when it's on a skirt and the waistband covers to become the stop. Off the bottom when doing closures on pillows, etc. That's my opinion, and it oughta be yours!

well I've learned something new today! We have different techniques, as long as the end result works, it's all good. Thanks to all who responded w/ differing instructions. OP, did your pillow come out for you?