The subject line was too long for a comfortable display so I trimmed it. Does the new subject line still describe the question adequately?
You posted this in the Consumer section but I can't tell where it should best go to get an answer. Is this for the Consumer version of McAfee or are you running an Enterprise or Business version?
You should open the VSE console and create an exclusion with the filename and for each extension that you want to get detected since the user defined rules does not accept wildcards. So you should create the following user define rules:
If you want to detect any file which starts with abc, you must know and define the complete filename like this, abchello.dll as I said before user define rules does not accept wildcards. Do not worry about the path as it will be detected in any path if the filename (defined by you) it is found in any path