You need to build the data maps between CRM and SFDC. If their installation of SFDC has been customized, most likely you're going to have to also make sure there are matching custom entities in CRM to receive the data. Then it's all about
deploying and testing the data map until everything is right.
Definitely use the CRM Online sandbox environment first, so you don't mess with any production data when testing and configuring Scribe and CRM.
There's no real shortcut for this, you just have to get in there and make the data map.
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