I was taught to use the opposite hand with fingers closed and palm out to approximate the AIM method. For example if I was going to be entering a standard holding pattern, I'd hold my left hand to the HSI, with fingers closed and thumb at it's open position. If the reciprocal of the inbound leg is below the thumb line it's a direct entry, between the pointer and the thumb-teardrop, pointer around the horn to the thumb line-parallel. It's complicated to explain but easy to demonstrate when you hold it up to the HSI drawings you have linked. It'll get within the "conveniently aligned" WAG satisfying the 11-217.