Hi
What I did is just deatach / attach database, created user, assign right permission to this user for this database and then changed ODBC connection that pointed to the new SQL server. I would suggest that you also upgrade to new vCenter verision, because new vCenter reconfigures database and also creates new jobs. If you would not do this upgrade, than you have to run sql scipts defined by vmware for creating those jobs.
Everything else you can find in documentation.
Good luck, Dejan 
