mapping with www. prefix

Hi there,

I'm using the domain mapping plugin which works great, apart from one thing:

Right now,

subdomain.maindomain.com is mapped to
http://subdomain.com

However, I'd like to have it at http://www.subdomain.com (with the http://www.prefix)

I can remember finding a post about this, however I couldn't find it when searching the forum. If there's any workaround/hack for this, I'd be more than happy,

Thanks
Robert