If i'm following. Take your outside leg and put inside on his thigh. And your leg between his hooks over the back of the same leg. As he goes to sit out kick the in hook hard in to him and hook your foot upwards. At the same time start to shrimp your hips out. Most people react and leave space for you to get your bottom knee back in for guard
I used to struggle here, but (my right leg is between his) most guys dont control my left arm.
I palm his left traoezius muscle and drive his head toward my lower body by driving my forearm bone into his neck.
now my left knee come up near my face and I hook the leg over the back of his neck.
By contracting my left butt muscle I am pushing him away, he will get to his knees as my right leg slides under him and I get guard.
There is a gi choke there but I havent seen it mentioned(though admittedly I read just half the posts).
The available choke is the hellchoke.
After(or as) your leg is getting over his neck your left hand(or right in a more complex variation) reaches for his right lapel.Now you kick your leg extended.
I haven't done gi in a long time and kinda suck at it now so I can't tell you much in the way of intricacies.I'm just saying I saw the choke done from under that position somewhere.