Hmmm. It's been a good year and half since I did that work, so it's getting a bit hazy in my memory. I think I purchased two cans of aerosol solvent and used them exclusively for flushing components which I left installed in the car - namely the evaporator and the hi/lo lines to the evaporator. Everything else I removed from the car and just used a funnel to pour in lacquer thinner.
I recall reading on a web site put together by an a/c shop owner that they use mineral spirits for flushing (cheaper than lacquer thinner, but not as volatile and hence more work to remove). They just introduce it using one of those pointy tipped plastic ketchup dispenser bottles, then use a blow gun with compressed air to blow it out. The flush gun is a nice tool, but I don't think it's really necessary.
Anyways, I think I used a full can of flush just for the evap, a good 12 ounces or so. Lots of black gunk came out of the evap, though there was no visible contamination of the rest of the system.