No, you can't do it across the WAN.

In that scenario, Windows Terminal Server is a great solution.
Anything else is going to be largely a waste of time and effort, and
it's going to be hard to maintain.

There are 3 very important issues with regards to using Access as a
mult-user database on a network:

1. Build a well-designed, normalized, properly indexed, database.
2. Install it on a high-quality stable network that well maintained.
3. Train users to not do stupid things like leave their machines on over
night, or turn them off without properly closing down.

Access will not run quickly over a WAN unless you either access it with an
asp or asp.net application, or use terminal services. Of the 2, I prefer the
second because it cost far less and deploys the same database that you've
written for the LAN. There are a few experts here on using terminal servers
(myself, Steve Shapel, and David Fenton come to mind) so you should have no
trouble should you decide to go that route. But first things first. You need
to learn some basic database principles (I suggest books by John L. Viescas
and Michael J. Hernandez as starters) then build a good database. We're here
to answer specific questions when you need some help.