I work at Wal-Mart distribution center in Shelby, NC. I want to get a loan on my 401k plan with Merrill Lynch. I want detailed information on this. I have been trying to find out this information for a month now.

Have you asked the Benefits administrator for your store or district? They can tell you the rules and provide the application form.

This site contains a phone number for the plan administratirs:
Wal-Mart Profit Sharing and 401k Plan | Form 5500 by BrightScope

But I would be very surprised if there isn't an employee website you can use to apply.

Yes, Walmart has very good HR, this surprises me that there is not a onsite HR that would merely have paper work.

But Scott has provided you with great info. Also you should have been given detailed info when you signed up.