SCM 3.0 is a powerful tool to create System Center Configuration Manager 2007 and 2012 DCM Baselines. However, because SCM can only convert a setting to a corresponding DCM setting if SCM has an associated template the following section will outline an approach that maximizes SCM's effectiveness.
If your goal is to convert a custom GPO that is similar to one of SCM's built-in baselines into a ConfigMgr DCM Baseline, SCM can provide a great library of DCM CI's to start from. The following steps outline this process:
Import a custom GPO into SCM
Do a comparison within SCM between the custom GPO and the appropriate SCM built-in baseline to provide a breakdown of which settings match and which ones don't. Export this analysis to a spreadsheet for easy access throughout the process.
Within SCM, duplicate the appropriate SCM built-in baseline. This baseline is the starting point for your eventual export to DCM.
Based on the SCM compare (from step 2), in the duplicated SCM baseline modify any necessary values where the setting is supported in SCM and has a value difference in the GPO and the SCM baseline
Based on the SCM compare (from step 2), in the duplicated SCM baseline remove any settings that are not in your custom GPO. We have now have completed the two types of modifications that can be done within SCM without complicating the export to DCM.
Within SCM, convert the duplicated SCM baseline to a ConfigMgr 2007 DCM cab. Note that this format can be imported into ConfigMgr 2012 which will automatically upgrade the format to ConfigMgr 2012. Keep this in mind if you have both 2007 and 2012 in your environment. If this is your scenario you may want to do modifications in ConfigMgr 2007 since once in 2012 you cannot move modifications back to 2007.
Import the DCM cab into ConfigMgr
Within ConfigMgr DCM, add any additional settings that are needed based on your documentation from the SCM compare (from step 2)
In this way you have a great collection of ConfigMgr 2007 or 2012 DCM CI's to start from and also have the documentation for what needs to be added.