BD's brake is air activated so either a tank or compressor will work. I have air bags on my truck so instead of 2 compressors, I have a tank. It's switched completely independent from either the bags or the brake. I have a master switch in the cab that can turn it off, and a pressure switch that turns it on when necessary. The brake comes with a regulator that keeps the air pressure from being to high (for the brake) so all I needed to do was run a line from the tank to the brake. You should be able to do the same with other brands of brake as long as they're air activated, I only know about the BD brake though.
I bought my tank from an online store, something like "macsspring", couldn't find it but the name is close to that. They have a big selection and they can answer your questions over the phone.