If you already know you can turn it off for a limited time then you should see the option to turn it off until the next restart or never.
Double-click the taskbar icon to open SecurityCenter Click Advanced Menu (bottom left) Click Configure (left) Click Computer & Files (top left) Turn it off in the right-hand module and tell it for how long.
You cannot do this..!!..This is also not recommended...If you want to turn off realtime scanner then it can only be set permanently off..McAfee home products do not have exclusion option, enterprise product do have it..!! But what McAfee does is logical and good..otherwise if something goes wrong like system unstable or unusual behavior then people will blame McAfee...You can send that file to McAfee for analysis and also check which scanner detects it. like on virus total and threat expert, atleast on threatexpert you can check it's behavior..