For the datasource definition see the kit (or in git) under docs/teiid/datasources/salesforce/ In particular there is the salesforce.xml snippet.
The simpliest VDB.xml:
<vdb name="test" version="1">
<source name="sf" translator-name="salesforce" connection-jndi-name="sfDS"/>
That will just to the default metadata import.
Apologies for the delay, had some different technical issues to deal with first. We've been able to successfully set up salesforce in our simple xml deployment in 8.3. Thanks for the help!