You could give that mix a try. I would be wary of putting too much manure in the mix--I would experiment. But perlite sounds good for drainage.

They grow well with warmth and moisture, so try them in a spot that won't dry out too much. They also like regular feeding, which is where the manure will help. I like to use Osmocote and then some liquid fertilizer on occasion.

Colocasia like a lot of bark in their soil. I always add extra bark when potting mine, using the small, fine bark pieces.