This depends on what data you want to transport as it can be quite complex when looking at everything that is linked to the incidents , change, problems and all the collections like notes, resolutions.
Normally this is done via bespoke scripts that are written Professional Services which you would need to speak to your account manager about.
If you just want the raw data for example with incidents just Summary and Description , category, you can export to a excel spreadsheet and import as new incidents, you would have to make sure all mandatory fields are populated and the lifecycle is populated. Just so you know this process would not trigger the SLA.
You would need to plan very carefully what you require.
I am interested to know what problems you had with the upgrade.
This is what we tried with support.
Our database version is 126.96.36.19940 and our application is running 7.8.5570.35315. Even after running the MDM the database is not upgrading. We checked the log and nothing is even being logged.
So then we went to their test server, created a new instance and pointed the framework to production and ran the mdm and it still did not upgrade the database version. This time it did log that it ran the MDM but a lot of the commands were Ignored.
We then set up a sql trace through sql profiler and ran the MDM.
So we have decided not to more the data over and we are starting with a brand new instance and keeping the old archived.