Hi David,
From what I've learnt you need to create a group on e-smith for your admin account. You can call the group anything you want so long as it makes sense to you. Make the users that you want to be admin a member of this group and any other groups that you have created.
Then in your "smb.conf", you will need to add a line somewhere that looks like this,
domain admin group = @xxxxxxxxx
xxxx = group that you have created
You must use the " @ " or else it will not work. It gives a basic admin account. I have not tried it to its fullest extent.
Hope this helps,
Karl