If this is in the home version you cannot. all you can do is submit the file to mcafee and tell them it is a false +ve. you do this as follows Submit as per
When they reply immediately says it is malware reply to that email changing the subject to False+ve and name of detection.
In body says also why you feel it is a false detection.
Make sure the analysis id is in the body still and post that here.
The ony way to trust a file is get it detected as a potentially unwanted program then you will get the option.
In the corporate version I think you can trust files.