Two approaches that I've seen for conventional soldering iron
mounting involve what I'll call "flood and suck" that involves
covering all of the leads on one side of the QFP on the PCB with
solder and then using a solder "sucker" (such as a Soldapullt) to
remove the excess.
The other approach uses solder wick (solder removal braid), laying
the braid over the QFP leads and PCB and heating and applying solder
*through* the braid to the leads.
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I've used "flood and wick" successfully applying liquid flux before
the "flood".
I suspect soldering through braid accomplishes the same thing.