I ordered an accessory set from eBay (China) which arrived yesterday. Tonight I hooked up a foot pedal switch and after some head scratching, determined it was normally closed instead of normally open. Fortunately, the internal switch was SPDT, so I moved a wire and I was in business. The only remaining complication was a non-standard air-inlet fitting. Some 3/8" ID tubing slipped over the end of the fitting, secured with a screw clamp.
I thought that the "business end" was a piston, but it's much simpler than that. A plastic cap is pushed into the syringe, forming an airtight seal above the solder paste. The air adapter locks on the top of the syringe with an o-ring seal. Air injected into the cavity at the top of the syringe forces the paste out.
The dispenser automatically times the air pulse when the foot pedal is pressed. This time, the air pressure and the needle diameter work together to control the size of the dot. I found about 60 PSI air pressure, a dispense time of 0.17 seconds and a brown needle (unknown gauge, came with the solder paste) seemed to give me decent results.
The paste didn't want to stick to the board. After some trial and error, I found that holding the syringe almost vertical (almost perpendicular to the board) and actually pressing down a bit gave me decent dots of solder. Other solder paste may work differently.
Once I had the technique down, it took only a few seconds to apply solder for a MAX7219 on one of my display boards. After that, I positioned the IC in place and used my hot air station to solder the chip down – man, this was so much easier than using an iron! It took only a few seconds to heat up the solder.
The results from my first trial weren't perfect, as you can see from this picture. Two small solder bridges can be seen on the IC; these could be easily fixed with a soldering iron
A solder paste dispenser and a hot air station are highly recommended if you're using SMT parts. Bargains like my Goodwill find here don't come around often but the low cost (about $100 each) will provide serviceable tools.