I managed to use Cheat Engine to get favor using the method Remi Hiyama mentioned.
The way I made it work was going through the process of starting a session normally, but going into the "Request Favors" menu when you get the option (should be right before actually beginning the session)
Within that menu, open up any tab you like that has more than 2 items.
Separately, open up Cheat Engine and point it to the VS executable.
Start a new scan with Value Type: Float and Scan Type: Exact Value, make sure Value Type is set correctly to Float, Scan Type should be Exact Value by default, but Value Type is not usually set to float.
Back at VS, the value showed at the bottom labeled Cost that changes when you select/deselect items on the list should be the value you use for your new scan.
Then, change that value by selecting/deselecting any item on the list, and perform a next scan with the altered value; repeat until there are only 3 values found on Cheat Engine.
You can then edit those values within Cheat Engine to a negative number, which will be the favor awarded to you after that session ends.
You do need to start the session for the favor to be modified in the save file, but you can quit halfway through or just enjoy your time.