Asset Browser custom preview

Hi, i have a simple question:
if I have a multi object asset and I want to make from the collection instance an asset I can, but I need to put on that asset my custom preview for better visual searching (so is for all other kind of assets, eg nodes groups etc…). At the moment if I try I receive the message data block not support custom preview.
There is something wrong in this my approach?
What is the best way to put macro assets and extended kinds (only for global reference between the standard ones) in asset browser?