Currently, Help+Manual supports the open-source Subversion system, Microsoft Team Foundation Server and Microsoft Visual SourceSafe. However, you can also use any version control system "passively". It just requires a couple of extra steps. This is possible because all project source files are plain-text XML, which is ideal for management in version control systems.
When you're using version control passively it is okay for all users to work on one working copy at the same time (local network only!) from Help+Manual's perspective. As far as HM is concerned, all users are just working on a normal project using its integrated multi-user editing features. However, it is essential that you check whether this is OK for the version control system you are using.
Check whether multi-user editing is OK with your VC system!
Allowing all your users to work on a single working copy may not be OK for your VC system. For some, it is an absolute requirement that each user should work on their own unique working copy on their own. So check with the person responsible for managing your version control system before doing this.
Never combine multi-user editing with HM's active VC support!
However, you should never use the single copy method in combination with active support for version control in Help+Manual. This is also not permitted. Help+Manual will only open working copies on network drives in read-only mode. This is necessary because trying to do with this would cause serious loopback problems on the server when Help+Manual is synchronizing between the server and the working copy.