Well... i don't think that is an issue.
TBS does support manual created subdomains.
If you do not want to use wildcards, but you want to use manual created subdomains, you only have to install TBS in that subdomain just as you would do it in the root.
However, because u are using a cpanel created subdomain, and not widlcards, your blogs will be created with folder addressing.
So your blogs will be like:
sub.domain.com/folder/blogname1
sub.domain.com/folder/blogname2
sub.domain.com/folder/blogname3
etc...
I appreciate the response, but the whole idea here is to not use folder names. From BS2's viewpoint apart from the DNS editing, is the support for subdomains just reliant on htaccess rewrite conditions/rules? If so I guess I could get someone to hack htaccess to support a defined set of subdomains.