[Webtest] Getting to Form Submit button in a table

[Mercer Kip]

I'm looking for a way to get the submit button for the 
following xpath.  

XPATH: /html/body/center/form/table[2]/tr[4]/td[2]/input

I'm not able to modify the web page in any way.
I have not been able to figure this out, is it possible
with Webtest?

Thanks for any help 

Kip