You are pretty limited for things you can load in LT. Just to get the easy stuff out of the way - have you tried using REFEDIT for directly editing references in your drawing? Could you go to your xref manager, right-click on the xref in a list and select open? I'm not really sure what you can do in LT.
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.