Well I have been trying to get better at knee on stomach more precisely the chokes from said position but I seem to lose control of the position when I try to go for the choke.
Usually the way I try to control is by holding on to the collar behind the head and by grabbing the near leg at the knee.
So what are the steps for the cross choke so I don't lose control?
With the leg that's on the guy, I tighten my foot to his belt, put my knee on his sternum, and make sure my hips are forward. Reach in with the same side arm (as knee on body), reach in with the other side (thumb in, not grabbing shoulder cloth or anything), straighten my wrists and finish the choke.
Keep in mind I could be doing this completely incorrectly, so don't take this as expert advice.
I think there are a lot of schools of thought on the knee on belly.. Personally, I have my knee on the solar plexus and my toe just touching the ground so I can shift weight on and off. My fot is at his hip so I know what he's doing with it (I have long lower legs).
To get the cross choke (with right knee on belly), start with the cross-lapel grip with the right hand and control the right sleeve with the left (pulling up hard to make turning in difficult). At your leisure, release the sleeve grip with yur left hand and reach over his far shoulder to get a good chunk of cloth. Sprawl your legs back.
He should be on his side facing you and your right hand should be under his chin with the collar gripped. Left hand grippng his left shoulder, finish in the usual fashion.
I was taught that in order not to lose control of the guy when you transition from knee on stomach to the cross collar choke, you should put your head on his far shoulder (so he can't turn onto his hands and knees) and your knee up against his hip (so that he can't pull guard).