So let me get this straight:

You want parts of a program to reside on SSD, such that you click on the game to load, those specific parts are loaded into RAM, and while that happens the REST of the parts are loaded in from the HDD?

"Dynamically loading from HDD to SSD before RAM" is the extra step I'm talking about. It's not needed. SSDs are faster than HDDs yes but transferring from HDD to SSD to RAM is going to be MUCH slower than transferring from HDD straight to RAM.

That extra step is not needed, will cost more to add that extra hardware, and the software isn't even created yet.

"Possible" does not mean "probably" (or "worth it" or "practical") and in this case it means none of the above.