You're right. It's not a picnic. From memory this is a way to adjust one or both of the drop glass guides:
a. Start by getting the carrier onto both guides simultaneously. For some hints about how to do that read
this linked thread while you wait for your parts to arrive.
b. Don't mount the regulator to the carrier yet....for adjusting the guides you'll raise the glass by hand. Drop the regulator down to full-open position so it doesn't scratch the glass while you're aligning the guides.
c. Each guide has two adjusting nuts, one that orients it on the door beam and one that tilts the curved rail. Leave them both a bit loose at this point.
d. Run the drop glass/carrier up by hand until it snugs into the felt channel. Use blue tape on the outside to hold it up, connecting the tape to the fixed glass (mask the tape from the painted channel rail first so it won't peel any of the paint off later).
e. Wiggle the rail and the bracket a bit til you think they're aligned to the carrier with the glass up. Tighten the rail and bracket nuts.
f. Pull off the tape and check that the drop glass goes up and down smoothly by hand. Be careful not to let it fall all the way down. It's very hard to re-load it onto the guides from below. If the glass doesn't run smoothly and lift into the channel at the top then try again and adjust the guides with the glass up.
g. With the glass and rails aligned move the regulator to the half-up position, reconnect the regulator bracket studs to the carrier and secure them.
Done.
This is all easier to do if you create a door-to-rear striker pin rope that will keep the door halfway open while you face it while sitting in either of the seats with your legs over the door sill. My rope has an adjustable loop at the bottom that loops under the striker pin and a metal hook at the top that engages one of the door cutouts. A light metal chain can work, too.