can Domain Mapping support subdomain?

Hi, i am using subdomain in my WordPress network sites. I would like to separate my main site and shopping cart. Can i create another subdomain in Domain Mapping and point it over to the shopping cart?

eg:
mainsite.networksite.com --> http://www.mainsite.com
store.networksite.com --> store.mainsite.com

is the example above the correct way of doing it?

Adam