Install adminpak.msi from %logonserver%\admin$\system32 and use the ds-commands like below. dsmod neads the userDN which can be piped from the dsquery-command.
dsquery user -samid | dsmod user -hmdir \\server\$ -hmdrv G:
As you want to create the user, you can set all the parameters directly with dsadd-command:
dsadd user -samid -upn @domain.com -fn -ln -display " " -hmdir \\server\$ -hmdrv G:
If you want to add the user to a group, you use the 'dsmod group'-command:
dsmod group -addmbr
or
dsquery group |dsmod group -addmbr
Use 'dsquery user /?', 'dsmod user /?' or 'dsadd user /?' to get help for the commands.