Depends on what your trying to do.
If all you want to do is add files to the exclusion list then poking around in the registry is the wrong place to start. Anyway with 'Access Protection' enabled you won't be able to make any changes manually.
Add the exclusions into an ePO policy or using the VSE console. Let the software up date the registry.
As for a defualt exclusion list i don't there is one as such. In the end it depends on what the computer/server is doing. There are plenty of Knowledge base articles for best practice exclusions for Exchange, SQL, IIS, Back-up Exec...etc.
https://kc.mcafee.com/corporate/index?page=content&id=KB66909 <- Start here. This is the master exclusions knowledge base article
https://kc.mcafee.com/corporate/index?page=content&id=KB51471 - Exchange 07/10 as an example
Is it possible to add few items to the exclusion list using McAfee exe via CommandPrompt?
I am planning to creat a batch and want to run in silent mode (without user interaction)