We are using UE_6.24.11.
The tempStoreInMemory option in daa-meganizer has been replaced by

 -cs, --cacheSize [number]  Cache size for SQLITE (use with care). Default value: -10000.

Can you please advise how to use this to achieve tempStoreInMemory=true? In what units is 10000?

The value is passed to SQLITE as cache size, as discussed here: