This video shows how devotees celebrate Vamana Deva's Appearance Day in ISKCON Mayapur temple in a very original way.
This type of worship of Vamana Deva was introduced by Srila Prabhupada Himself, He had instructed Jananivasa Prabhu to select a small boy, around 4-5-6 years old to take the part of Vamana.
Then the whole worship is performed - as usual when we worship Vishnu tattva.
The boy is concidered to be Vamana Deva and worshipped as such.
This is how Srila Prabhupada wanted this ocasion to be celebrated here in Mayapur. I really don't know if this is apply to other places or not.
If you have more questions regarding this, write to our head-pujari, Pankajanghri Prabhu