If you understand what are doing then certainly you have enough skills to edit a plain text file. We are not talking about some tedious work that you have to do repeatedly. Turn it on, if you like, and that's it.
BTW: Speaking about ad-munch, hmmm, previous versions did not work quite right with webshield as far as I remember. Their new version might work properly today -- perhaps there is time to re-evalute this software and possibly add it to the Optin process list.
Again, you can do it (just once) yourself in the configuration file. (avast4.ini) Simply edit the OptinProcess option or turn the Optin off, it's up to you.