I have done the tape and cast thing on the last few rods I have built. I found it really helped me when laying out the guides on my last 2 wt. build. The guides were falling on or very close to the ferrules when I used the standard guide spacing charts. I also like the confidence I get when I can test cast the rod before wrapping the guides. I suggest tapeing under the guides and doing the needed prep work on the feet so you do not damage the blank.  
Coachscott

I go ahead and wrap my guides on the blanks but don't add the finish.  I then take a length of 20 lb test mono and thread it through the guides to the reel seat.  I then hold the mono against the reel seat and pull the other end to see the bend.  You have to be very careful not to break your furls though, even though they are wrapped also.  This way I can see the contour of the bend plus the gentle force will align the guides.  If this is satisfactory I'll then put on a reel and actually cast the rod.  I know some rod builders recommend against this as they don't want to damage the furls but I've never had a problem with it.  Just my 2 cents.

I just use thread.  Basically the rod is completed with the exception of the two part finish.