Have fix group of users flag / vote on a node to trigger sth ( workflow state change)

In our company's workflow we need to check if for a certain content the four or five expert people have read/checked the content and click a okay button/link .

This would trigger ie. a workflow state change.

Any idea how i could implement this? Maybe it's easy using flag module and a fix rule where these people are hardcoded, they are always the same.

florian