It seems using VBScript and GetObject does allow it, however that's a very simply enumerate_groups VB script, all it does is enum members of the domain admins group.

Code:

On Error Resume Next
 
Set objGroup = GetObject _
  ("LDAP://cn=domain admins,cn=users,dc=forest1,dc=net")
objGroup.GetInfo

Set objGroup2 = GetObject _
  ("LDAP://cn=domain admins,cn=users,dc=forest2,dc=net")
objGroup2.GetInfo
 
arrMemberOf = objGroup.GetEx("member")
arrMemberOf2 = objGroup2.GetEx("member")

WScript.Echo "Members:"
For Each strMember in arrMemberOf
    WScript.echo strMember
Next

For Each strMember in arrMemberOf2
    WScript.echo strMember
Next


As I said above, this works - however it sorta seems to suggest that you need the exact DN of a target and as that's what I'm trying to get, it's sort of like chicken and egg.