You can do the listening part of the leak down test without the gauge.
You just need an air compressor and a spark plug adapter(usually you can use the hose for the compression tester if it has a quick connect fitting).
Just make sure you are at top dead center on the cylinder otherwise when you apply air pressure the engine will spin.
You want to listen to where the air is escaping(air intake, oil filler opening, exhaust pipe, pvc)
You won't be able to quantify the amount of your leak but you may be able to locate the source of the leak(s).
I made a leak down tester following Mike Nixon's instructions
www.motorcycleproject.com/text/Leakdown.html 
