Just found this great course put out by Seymour Duncan. It covers all the basics of guitar soldering, as well as general pickup installation guides for Les Paul, Strat, and Tele style guitars. Also includes a chapter on passive to active pickup installation. This is more that a set of tutorials - it's laid out as a free course.
tech.seymourduncan.com
Seymour Duncan Tech
We’ve been obsessed with perfect guitar tone for 45 years—shaping new tone, replicating tones, winding pickups, and recommending pickups. You learn a lot in a half century. You master some things. We mastered tone. We created this educational plaform to give you all the tips and tricks we know...
tech.seymourduncan.com