This is another trick used commonly in wire hacking, extra components to be soldered generally don't have a place to be mounted on the PCB, but doesn't get in the way of anything either, so in-line solder is used.
Prepare the lead and part to be soldered, the 2 joining leads is usually equal in length.
Put a segment of heat shrink tubing on the wire. I like to cover the part to be soldered with heat shrink as well for safety and looks, try to cover as much exposed joints as you can, even if the parts might be too big. If you plan to use electrical tape, you may skip this procedure.
Make a good mechanical joint first, you can twist the 2 leads together, or make a hook like shown in the picture. It is vital to have a good mechanical joint prior to soldering, because in-line components may be dragged around, so a strong joint is a must.
Pre-heat the joint for a few seconds then apply solder.
After it's done, use the hot air from a lighter (never use direct flame) or hot air gun to shrink the tube.
And there is the in-line mount, very durable and looks good too.