Yes, easily. Just add the domain to your DH account, and it'll create a directory in your webspace where you can work on the files exactly as if they were being served. The system doesn't know or care whether the DNS records are actually pointing to the files it's trying to serve.
If you want to test the site prior to changing the DNS servers, create yourself a free dreamhosters.com subdomain and set that to mirror the main domain. Then if everything looks good, you can just change the DNS records and everything will magically start working just like you want.