I don't tend to do this posture as often in Vinyasa krama as in Ashtanga, so had to relearn how best to get my arms through. Also I'm not as sweaty in the slower VK practice.
Here, once in lotus, I lift my left leg a little away from the right holding just above the ankle. this creates a little more space to get the first arm through. For the second arm I press the top side of my left foot against my right thigh flexing the ankle a little to lever the leg up a little thus creating more of an opening to pass the arm through.
A water spray on the arms and legs also helps.