It would be helpful and nice if a future version could include the ability to schedule custom scans. This would be a big plus for users who have backup disks etc which do not need to be scanned.
At the moment there are only two options. Remember to pull out all the drives not required prior to a scheduled full scan (which defeats the purpose of running a schedule) or elect to do a manual custom scan with a calendar reminder. I have opted for the latter as it is easier but at the same time makes shedule ability in McAfee completely useless.