I heard that you can't put a memcal in a VY V6 is that true? And if not where abouts does the memcal go?

You can if you have a VY with a factory-fitted L67 as shown in the link below:

http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/MEM613/SubProducts/MEM613

Otherwise, if you have an Ecotec, then the entire computer needs to be replaced as shown in the link below. The reason for this is the memcal is effectively soldered onto the circuit board, therefore it's easier to replace the entire computer instead.

http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/COMP609/SubProducts/COMP609