As I recall, SH member Fred Cronenwett published an article in
Model Aviation that showed how to do this.
For myself, when I came back to CL in the late '90's, I settled on the DuBro ignitors with the replaceable batteries. I've done it a few times, and just a week or so ago. Unscrew, remove battery, drop in new, screw back together...so easy a cave man could do it...and I proved it!
I've also used both NiCads and NiMH, and didn't care for the NiMH...they were always flat when I wanted to go flying. With NiCads, they may be flat, or they might be just fine, when the call comes to go. Eventually, I'll go with a plug in system with a mini-phono plug-in on the side of the plane. Alan Resinger showed us how to make a clip for the glowplug post that is compact, light and brilliant. He even gave me one. Thanks, Alan! I'll be using it next season, I hope. Power source will be a pack of Alkaline D cells wired in parallel.
Steve