Hello again Carlos,
I found where it can be downloaded and it was correctly installed for me. But... It is now in a google code repository. This means no real "warranty". By the name of the uploader, which really can be easily faked, it seems it's the same package that was in the marketplace. Here's the link:
mii-deployer - Eclipse plugin for SAP MII - Google Project Hosting
It's ok for me because I'm working on a demo but it would be fine, before using it for real, if someone could confirm us the legitimity of the package.
Kind regards,
Ibai