yes i have done it several times,
if you double the bag over it will hold nearly 2 bar.
2 bar coming out thru a leak makes a loud noise so its easy to find and then fix.
who knows he may have 3 or 4 leaks.
i know last time i did it i had 2 leaks
in regards to which hose it dosent matter as long as its a vacum hose.
ie the fuel reg, a ebc, bov line, they are all about 3 - 5 mm inside diamater which fits snuggly over your air comp nozzle.
simple tight seal that you dont need to hold onto
just charge it up with a couple squirts of air and then go hunting for leaks.