The solution to saving as you go along is not to "Save As" because that causes you to work in a new file name. The solution is to use "Save a Copy" instead. That gives you a backup, but keeps the current project's name the same for use with Dynamic Link.
However, to answer the original question, it is simple. Just select the new dynamic link comp in the project bin, the select the dynamic link in the sequence. Right click on the comp in the sequence and choose "Replace with Clip" and "From Bin".
Simple.
Steven
http://www.stevengotz.com