It is thus: after garbha pindasana - after rocking around in a circle - let your arms come out of their position between your legs in padmasana a little. For garbha pindasana, arms should be tucked through to above the elbows. Now pull them out to below the elbows.
After only one week of trying this, I was able to get up and stay for five breaths. Amazing!
But looking at this photo of none other than BKS "Light on Yoga" Iyengar himself, I see that he is below his elbows too.
I feel even more brilliant today!
PS. Today also is my most brilliant son's birthday (although I don't think he can do kukkutasana). Out of respect for his privacy I will only make this mention of it. Happy birthday Finnian!