Despite all the dire warnings in the manual, installing the off-board connecting plugs was really pretty straightforward. The only one which was slightly tricky was P1, since it would be possible to install it such that pins were not parallel to the board. However, once I got it seated correctly, I used an alligator clip to hold it in place and then soldered it in. The two-row plugs seated pretty much seated themselves.
P5 and P6 came with warnings about soldering each pin less than 3 seconds each, so as not to melt the plastic shells. I just made sure the soldering tip was really clean before I did the soldering and it really wasn't a problem. Maybe Elecraft can think about supplying plugs not so susceptible to heat damage.
Looks like one more stuffing session should finish up this board ... I'll post a picture when it's completed.