here are some different models of the guide type he's using:
http://www.ebay.com/bhp/singer-seam-guide
if your machine has a little hole, to the right of the needle, on the metal plate, you will be able to use one.
they aren't expensive. they're easy to use once you have calibrated the position you need and made sure the guide is straight (parallel to your feed dogs.)
i think just about any brand would fit, but it's probably safest to search for one that includes your machine brand in the description/specifications.