MOTM

>I've had success with these plugs by first filling the "cups" 
>with solder,  then tinning the wire leads, then heating the 
>solder filled "cups" and inserting the tinned leads.  Hold the 
>lead in place till the solder solidifies, and you should be good 
>to go.

Before soldering anything go find yourself a scrap of 1"x1"x8"
wood and drill yourself four or more 5/16" holes in it.  Clamp
the wood in the vice and insert 1/4" plugs into holes.  THEN,
fill the cups with some solder.  If you practice a bit and have
good wire, you may be able to avoid pre-tinning the wire itself.
I did over 160 Neutrik TRS connectors this way.  By insulating
the connector from the metal vise (or your fingers) you prevent
the heat on the sleeve/ground from dissipating quickly and making
a cold solder joint.  Now, only 200 or so Neutrik connectors to
go.  (I won't even tell you how much a bag of 350 TRS connectors
weigh, or worse, how much it costs)

-Cary