You can use the vsx_provisioning_tool to export in CMA1 the current VS config (interfaces and routes) to a text file, adjust the textfile to what you need to have different and then use the provisioning tool again in CMA2 to create the VS again by using the file as input to the vsx_provisioning_tool.
There is a separate document on the Check Point site for the VSX Provisioning Tool.
I used it this week to migrate a VS from old hardware to new hardware. The migration was as simple as removing VLAN's on the trunk on the old hardware and adding them on the new hardware, for switches you create a copy of the switch with a dummy VLAN behind it on the old and the new cluster.
This method was also used when we needed to migrate a customer from a VSX cluster to a Maestro VSX environment.
Regards, Maarten