convert from single site to multisite (network) with existing subdomains

We currently use wordpress to manage our website under our main domain.
We also have a few subdomain under which different applications run.

www.example.com // our main website, running wordpress
extranet.example.com // a custom-made LAMP application
forum.example.com // another LAMP application
*.example.com // anything can happen in there.

We would like to use the Network feature to create subdomains in which each team can have its own communication tool based on wordpress + buddypress.

Question: can i convert our main wordpress installation to Network with subdomain, without removing access to extranet.* and forum.* ? I read the manual, but it doesn’t address the specific case where subdomains already exist and i’m afraid to break things up.

This seems possible to me. Most of this is related to server management and not only WordPress, so probably Server Fault also has interesting info on this.

On the DNS side, you would create a wildcard to the server with WordPress, and define your other subdomains to the servers that host those (some or all of them can be the same as the WordPress server). Wildcards always have the least priority.

For the server side it is useful to know that if a request reaches Apache but it finds no matching ServerName or ServerAlias in a <VirtualHost>, the first virtual host is returned. So you configure the WordPress setup as the first host and the others running on that server after it.