LT does not have an OPEN feature in the XREF pop up window, and you can not double click on the xref'd file and make it active for editing like the full version can. I have not tried typing in REFEDIT in the command line in LT yet, in fact I didn't think to see if that would work. I'll try it when I get back to the office.
I was hoping someone out there figured out a script that would emulate how XOPEN works.