I'm not sure what you mean by cam tower, but I recently rebuilt my v12. I do think that you'll have to release the tension in order to get the cam gear attached to the holder (to keep the gear from falling down in the timing chest). You'll also need to use the tool from JCNA to hold the cam gear in place. It's pretty easy to do. Definitely don't let the gear fall into the chest. That area is really tight and you'll have a hard time getting it out of there if you do.
