S2PX is separate to MettleCI. Its components are…
a plugin to the MettleCI Command Line Interface which provides analysis and conversion functionality, and
a set of Asset Queries which support the analysis command
You don’t need to upgrade any other parts of MettleCI to use S2PX. In fact you don’t necessarily need to install MettleCI to use S2PX, but you do need a commercial entitlement to MettleCI to use S2PX.