I've done this using a custom MIB poller, but not all my devices reported their model number and serial number. I set up two pollers, one using the chassisId MIB (184.108.40.206.220.127.116.11.6.3) and one for chassisType (18.104.22.168.22.214.171.124.6.1). There is also a file in the content sharing zone that is Cisco specific (Cisco Serial Numbers) but I had better luck with our devices using the above MIBs.
After you get the customer MIB pollers assigned to your nodes, you have to create a custom SQL report in report writer. (Or, if you're like me and only know enough SQL to be dangerous) you can hack the SQL statement posted by Vic Cato here: Getting serial numbers into node details & reports.
There might be better ways to do this, but it got me what my manager needed. I never went back to try and make it pretty. Hope this helps.
Thanks did not see the other post. I will give it a shot thanks!!!!