multiple SMF installations (with different DBs) sharing single login?

[Rasyr]

Like the subject says, is it possible to have multiple installations of SMF that reside different servers (i.e. have different URLs) share a single login among all instances of the forum software?

For instance, I have two websites. each has their own set of forums. I want folks to be able to go from one site to another without having to log in on multiple forums.

Is this possible?

[H]

Different forums can share the same database.

It would work better if they are  on the same server / in the same datacentre otherwise the login will take ages as it will have to contact a database server on another part of the internet

[Rasyr]

They are in the same datacenter, but I have no idea if they are on the same physical machine or not.

The company I work for runs three different websites. Two of them have forums, and the third site does not have its own forums, but links over to the forums on the main site. All use the same host.

So how would I go about using the same login for multiple forums?

[H]

I believe there was a post somewhere about how to actually set up the user sharing. Basically all it involves is changing a bit of code so that there is only one user table used.