by Terr on Tue Sep 28, 2010 9:17 pm
If we're talking about the 3.5mm plug, then it should be extremely straightforward on an electrical level. You'll still want a multimeter to make sure you're not swapping around the common/left/right wires when doing your soldering. (I'm assuming you have a 3.5mm plug with a length of wire on it that's being scavenged from somewhere.)
The tricky part will be structural: What stresses will happen on your soldering work? Consider shrink-wrap tubing, as well as some way to avoid putting any yanking strain on the join. (Like a knot leaving the join on a slack spot.)
It's the 3.5mm sockets where things get a little dicier, particularly with the varieties which either do auto-switching from another circuit or else have a softer "is something plugged in" switch line as part of the mechanism.