I'll be installing a silverware drawer in my tear drop galley soon. I bought this a set of drawer slides from Rockler and a set of face frame brackets.

According to the instructions, this is how they are supposed to fit in my cabinet.

My question is how the heck do I align the rear brackets to keep the slides parallel to each other and the same height. This seems especially tricky since, I'm working inside a confined space.

If anyone out there have any tricks, tips, or other advice to help me out, I'd really appreciate it.