Actually, it doesn't. (Sorry, it's been a little crazy here.)
My problem is at the step where you convert Multichannel to Greyscale. It either asks if I want to discard the other channel(s) or it changes only 1 of the 2 channels to greyscale. In this case, if I then convert to CMYK, I end up with 5 channels -- CMYK and the other spot channel. Then I choose Split Channels from the arrow thingy (the Help files say you can only Merge Channels from multiple greyscale files of the same size open at the same time). But then I'm stuck because I had 5 channels to begin with, and if I select CMYK, I lose that other spot channel all together. If I Split Channels before converting to CMYK, I can only merge back into a Multichannel file.
AND, if I go ahead and merge the CMYK channels created from the first spot channel, it just turns it into full color black. It doesn't make it look like the PMS color that was originally selected... I'm at a total loss here.