Is it possible to do a WP Multisite Install at a subdomain?

I am having quite a lot of difficulty with my multisite installation on my primary domain. I will be running BuddyPress on a subdomain and realize that this is where the multisite should have been installed.

Are there any special instructions for that?

How does one set up a wildcard at a subdomain for the multisites?

Do I need to do anything special during installation so that the network sites will be automatically set up as subfolders, like