yes you can dcpromo the server without a network. You'll have to have your nic configured. Since you said you have no network enviornment, i'm assuming no router is leasing dhcp to you, so configure your nic with static information. Make your ip address whatever you'd like, for example, 10.10.10.10 and your default subnet would then be 255.0.0.0. Set your dns server to 10.10.10.10 since when you dcpromo, an active directory database is dependent on dns, and when you dcpromo, dcpromo will install dns for you, and your own server will be the dns server, which is why you want the dns field to point to itself. You don't have to have dns configured prior to dcpromo, since dcpromo detects whether it can find a dns server, and if it doesn't, it sets dns up for you.
So...
1. Configure your nic
2. DCPROMO > let dcpromo setup dns
3. Have fun playing cause your computer is now a domain controller.