accessing data in backend workbook over vpn, is it possible?

I work for a small company that is working in 3 different cities. We
have need for select people in each cities to enter work reports and
other info into one of several spreadsheets. The company has not
purchased Office pro and does not have Access. I would like to
separate the data and the various macros into separate workbooks. I'm
hoping that I can make the workbook holding the data a shared workbook
and then load/edit/save the data from the "front-end" workbooks over
our vpn. Is this even possible? If so, can someone please point me
to resources that would help with pulling it all together.
Thanks