Using my previous reply you can do this without need of any custom object:

SAMPLES>read xml
<?xml version="1.0" encoding="UTF-8"?> <session> <session_Id>124364</session_Id> </session>
SAMPLES>set rdr=##class(%XML.Reader).%New()
SAMPLES>do rdr.OpenString(xml)
SAMPLES>zwrite 
 
%SAX=1
%SAX(1)=2
%SAX(1,0)=""
%SAX(1,1)="1" ""
%SAX(1,2)="!>A"
%SAX(1,"N","http://www.w3.org/2001/XMLSchema-instance")=1
%SAX(1,"d")=4
%SAX(1,"d",1)="session"
%SAX(1,"d",2)=" "
%SAX(1,"d",3)="session_Id"
%SAX(1,"d",4)=124364
%SAX(1,"n")=1
%SAX(1,"n",1)="http://www.w3.org/2001/XMLSchema-instance"
%SAX(1,"v")=6
rdr=<OBJECT REFERENCE>[1@%XML.Reader]
xml="<?xml version="1.0" encoding="UTF-8"?> <session> <session_Id>124364</session_Id> </session>"
SAMPLES>

Hi @Ben Spead !
My personal congratulations to see you here!
Working with you and your team on the worldwide HERMES project was one
of my highlights during my time at InterSystems.
It was due to your interpersonal skills to make this team so successful.

It was so special to me to participate and share this experience.
As a Sales Engineer with no local office I often felt "at the outer border of the milky way".
Not lost in space but almost.
But working in your team gave me the feeling of a "technical home".
As Engineer I enjoyed to style and create a product.
Which was more important to me than to consult, advice, and teach how to use some features.

Big THANKS for that!

Robert   

from class documentation:

You can import files exported in

  • XML format,
  • %RO format,
  • CDL format,
  • UDL format,
  • %GOF,
  • and CSR/CSP files.

You should do an export of one of this types and then see
how this may match your .vm  thing.

Your screenshot is definitely some XML
But it doesn't match any formatting structures or rules required  in IRIS or Caché.