Ad-muncher uses an optin method too. But the list of approved processes is rather long in ad-munch. I've reviewed that and it includes many types of IM soft, Winamp and Windows Media Player and some other which I wouldn't like to be enabled by default. At present I vote for manual avast4.ini editing for the ad-munch users. Sorry
To enable webshield scanning for Ad Muncher edit the avast4.ini file and add or edit this line:
[WebScanner]
OptinProcess=admunch.exe
Lukas