I don't know much about these things but my teacher once told me that when they had a problem with a spirit in a new property they used mahamrityujaya mantra and that successfully resolved the problem. In my own experience the 'bullshit' mantra can work well, that is strengthen your own mind against the suggestion of a curse, by just resolving that you are protected, cannot be harmed, and that the 'curse' is a load of BS. Namo Narayana
It's possible the book Iyengar is refering to in his article has now been printed and commented upon by Sjoman in his book The Yoga Tradition of the Mysore Palace. This book contains postures hanging from ropes etc and some lovely old photo's of Krishnamarchaya's training.