To set exceptions in AntiVir, open the AntiVir Configuration (Extras → Configuration) and activate the Expert mode first.
The exceptions are configured for the Scanner and Guard separately, so please select the corresponding module in the left panel:
Scanner → Scan → Exception
Guard &rarr Scan &rarr Exception
Then you can add files to be omitted for both Scanner and Guard in the configuration window. For Guard you may also specify processes to be omitted from scanning.