/HelpCol
Specifies which Help collection to load in Document Explorer. Use this switch if you have multiple Help collections, such as an MSDN Quarterly release as well as Help for a specific product, installed on a computer.
dexplore /HelpCol ms-help://<namespace>
Remarks
The namespace for a Help collection can be found in topic URLs. The set of characters after ms-help:// and before the next forward slash (/) denote the namespace of the Help collection.
For example, the Visual Studio 2005 Help collection namespace is ms-help://MS.VSCC.v80/.
Example
This example specifies that Document Explorer loads the July 2005 MSDN Quarterly Help collection.
dexplore /HelpCol ms-help://ms.msdnqtr.2005Jul.1033