usersessionset and usersessionget deprecated in SOAP V1 - What are the altenatives?

Summary:

We are taking preparations for the news of SOAP V1 APIs deprecating. In a specific project we have - we have a Library BML UTIL that used SOAP V1 calls (it called _configure on a product). We have made adjustments to make this now use SOAP V2. All works fine so far.

However! There are two functions used called usersessionset and usersessionget which sets a key and allows us to store a value.
These functions are no longer working - this is likely because SOAP V2 is no longer using session IDs.

Without this functionality, we are not able to pass information down from the configuration rules (which use usersessionset) and gets picked up in the Library BML UTIL code.