yes but you would use both elbows and dig into the theigh above the knees. If the person you are rolling with is more experienced i wouldnt throw the leg over ive been caught in trianagle a few times. the less experienced people usually are not quick enough. IF your class allows it you could...
YOu wanna move your knee to right under her butt and then dig your elbows into the theighs when the legs go down slide your other knee ovr her leg to pin it. You may be in half gaurd at that point keep wiggling and youll end up in side mount. If your fast you could reach behind and grab at her...