Make a jig to hold the wheel vertically at working height and able to rotate when temporary cross bar removed.
I used the 3M 5200 sealant, white, $16 from my local Home Depot. Enough for 5 rims.
And 3M 4412N Sealant Tape Roll - 2 in. (W) x 15 ft. (L), $26 from Amazon. Enough for four rims.
The sealant is quite thick at 66 deg F (19 deg C) and maybe I cut the nozzle oversize. Just run a bead around the nipple and fill the middle.
Don't touch it! It is super tacky. Do 1/3 of a rim and weight two hours keeping the blobs on top to prevent creep.
I waited until the sealant was firm, about a week, before taping.
I did mask the side shoulders/tire beads with electrical tape on the front rim.
Set up a simple spindle for a tape spool; easier to handle with two hands. Tape went on without problems.
On thing I discovered while cutting away the excess on the fornt was that the tape has a removable skin on the non-stick side.
Once that is removed the 2mm film is easier to roll tighter to the rim between the blobs.
I did use a little sealant around the valve stem inner surface, in addition to the o-ring.
Bought both the angled and straight 10mm stems. Because I use TPMS caps, the straight work better.
Three weeks now and pressures steady. And snow steady too.