This challenging task is not too bad once you get the hang of it. Here is how it was done today on Cindy's tenor.
Undo the strings from the tuners and secure the ukulele. Locate the center of the bottom seam and score the spot with the point of an awl to guide the pilot drill.
With a small drill bit make a pilot hole to guide the big step drill bit.
Switch to the step drill which makes a huge 1/2 inch hole in graduated steps. The hole is drilled through the end block.
Now drill a hole the width of the saddle slot in the bridge. The piezo cable must be led up through this hole to lay under the saddle. Scrape the saddle slot with a razor blade to be sure it is perfectly flat.
Insert a thin wire through that saddle hole and out the sound hole attaching it to the piezo cable of the pickup. You will have to draw that wire and cable up through the hole, not always an easy task.
Now hold the pickup barrel inside the sound hole, insert a long dowel of the proper diameter in through the drilled hole and into the bore of the pickup fitting tightly so as to bring the barrel out of the hole from within.
Now hold the pickup barrel inside the sound hole, insert a long dowel of the proper diameter in through the drilled hole and into the bore of the pickup fitting tightly so as to bring the barrel out of the hole from within.
the dowel has brought the threaded barrel out of the hole, the washer and nut have been slipped down the dowel and treaded onto the pickup and tightened.
Now the wire is gently pulled and the cable is coaxed out of the hole and laid in the groove of the bridge, the saddle is placed in the groove over it and the pickup is successfully installed.
'The final act is to thread the strap button onto the barrel of the pickup. I use MiSi pickups which do not need a battery getting power from a capacitor charged with a device plugged into the same hole that the amplifier cord plugs into. A 60 second charge activates the pickup for 16 hours of playing, Remarkable. I charged this one up and tested on the Amp. Works great, Installation successful.