How can I pass changelist number to ccollab admin batch xml as a parameter

I am trying to create a review in Smart bear collaborator automatically on perforce submission. For this I am using perforce triggers which calls admin batch with an XML file. I would like perforce's %changelist% value to be passed to the XML file. Here is the XML snippet for the review creation:

<admin_trigger_create-review>
    <review-id-regex>Review:\s+(\d+)</review-id-regex>
    <changelist>%changelist%</changelist>
</admin_trigger_create-review>

Obviously the changelist variable is not substituted and I have no idea how to pass it to the XML.

Note: I have a few other commands as well, so I have to use the batch XML for concurrency reasons.