Hello!
I've just wrote to the company who manufactures that gun... and they reply! They wrote:
"If you can use mouse under Mame you should be able to use our gun too"
I think I'll try to find a nearer reseller (as shipping cost from HK is more than gun's price) and I'll buy it.
Obviously as I can get it I'll post a neview and - hopefully - a confirmation it works under MaME!
BTW: where is the cheapest store to buy actlabs gun?
Thanks!