Hi zingy.rajeev,
Currently connecting Datamaker directly to VSAM is not supported. If you have an ODBC driver which supports VSAM, you might be able to. It is not necessary to connect Datamaker directly in order to work with VSAM.
Subsetting and masking VSAM is done in batch on the mainframe. You register the VSAM file layouts (from PL1/Colbol copyboooks) in Datamaker and create masking rules in Datamaker. These rules are then transferred to the mainframe and executed there. If it is necessary to load/unload VSAM files, this is done by running IDCAMS on the mainframe.
Have you checked out our online documentation set? This can be found here Mainframe Masking and Subsetting Jobs - CA Test Data Manager - 3.5 - CA Technologies Documentation
Please let me know if this answers your question or if you have any more.