ANSWER
*The ADS_SCHEMA_ID_GUID_USER GUID allows you to update the base user class details, including the employee id*
Based on MSDN article
The vbscript used to grant to the service account user the selected delegated rights:
REM #
REM # Delegate AD property set admin rights to named account
REM # Based on: http://www.microsoft.com/technet/scriptcenter/topics/security/propset.mspx
REM #
Const TRUSTEE_ACCOUNT_SAM = "ad\ADStaffUpdates"
Const ADS_ACETYPE_ACCESS_ALLOWED_OBJECT = &H5
Const ADS_RIGHT_DS_READ_PROP = &H10
Const ADS_RIGHT_DS_WRITE_PROP = &H20
Const ADS_FLAG_OBJECT_TYPE_PRESENT = &H1
Const ADS_FLAG_INHERITED_OBJECT_TYPE_PRESENT = &H2
Const ADS_ACEFLAG_INHERIT_ACE = &H2
Const ADS_SCHEMA_ID_GUID_USER = "{bf967aba-0de6-11d0-a285-00aa003049e2}"
Const ADS_SCHEMA_ID_GUID_PS_PERSONAL = "{77b5b886-944a-11d1-aebd-0000f80367c1}"
Const ADS_SCHEMA_ID_GUID_PS_PUBLIC = "{e48d0154-bcf8-11d1-8702-00c04fb96050}"
ad_setUserDelegation "OU=USERS, DC=AD, DC=COM", TRUSTEE_ACCOUNT_SAM, ADS_SCHEMA_ID_GUID_PS_USER
ad_setUserDelegation "OU=USERS, DC=AD, DC=COM", TRUSTEE_ACCOUNT_SAM, ADS_SCHEMA_ID_GUID_PS_PERSONAL
ad_setUserDelegation "OU=USERS, DC=AD, DC=COM", TRUSTEE_ACCOUNT_SAM, ADS_SCHEMA_ID_GUID_PS_PUBLIC
Function ad_setUserDelegation( _
ByVal strOU _
,ByVal strTrusteeAccount _
,ByVal strSchema_GUID _
)
Set objSdUtil = GetObject( "LDAP://" & strOU )
Set objSD = objSdUtil.Get( "ntSecurityDescriptor" )
Set objDACL = objSD.DiscretionaryACL
Set objAce = CreateObject( "AccessControlEntry" )
objAce.Trustee = strTrusteeAccount
objAce.AceFlags = ADS_ACEFLAG_INHERIT_ACE
objAce.AceType = ADS_ACETYPE_ACCESS_ALLOWED_OBJECT
objAce.Flags = ADS_FLAG_OBJECT_TYPE_PRESENT OR ADS_FLAG_INHERITED_OBJECT_TYPE_PRESENT
objAce.ObjectType = strSchema_GUID
objACE.InheritedObjectType = ADS_SCHEMA_ID_GUID_USER
objAce.AccessMask = ADS_RIGHT_DS_READ_PROP OR ADS_RIGHT_DS_WRITE_PROP
objDacl.AddAce objAce
objSD.DiscretionaryAcl = objDacl
objSDUtil.Put "ntSecurityDescriptor", Array( objSD )
objSDUtil.SetInfo
End Function
Function ad_revokeUserDelegation( _
ByVal strOU _
,ByVal strTrusteeAccount _
)
Set objSdUtil = GetObject( "LDAP://" & strOU )
Set objSD = objSdUtil.Get( "ntSecurityDescriptor" )
Set objDACL = objSD.DiscretionaryACL
For Each objACE in objDACL
If UCase(objACE.Trustee) = UCase(strTrusteeAccount) Then
objDACL.RemoveAce objACE
End If
Next
objSDUtil.Put "ntSecurityDescriptor", Array(objSD)
objSDUtil.SetInfo
End Function