The Comments field is only populated by manually typing information after scans have been completed. I can see how it would benefit you to have the tool acquire data from an additional SNMP field that hosts the information you have already added to each device. Specifically what field are you looking for the tool to grab?
You may also want to look at Orion IP Address Manager. This product is very robust and includes several features that would help in your situation. For more information, see http://www.solarwinds.com/products/orion/ip_address_manager/.
Good question " what field are you looking for the tool to grab?". Well, I will consider this software complete if the "Comments" tab will be populated automatically with information that already exist in "Computer description" tab in Windows 2000, XP, Vista and 7.
In my network, this field is populated with name of the computer owner and location, so... very important field!