How do you make them mine monero with 4 and something else with the other two?

A friend with 5 found a solution, that is working (at least for him). I am going to try it with the next restart.
After reboot - change virtual ram size. In his case he changed from 90 to 80. But I guess any change would do the trick. And then move sliders and confirm the HBCC size.

For me it worked with 5 once, when I upped the virtual ram from 64 to 80. That info I got from him have not tried yet, as I am very busy today, but will do with the next restart.
In any case, to make 6 work, it seems we need 96 or more virtual ram, and I simply don't have that much space on the SSD. Someone with bigger SSD should try it.