As long as you can get access to the ERP application through some kind of external web service then you can do it. REST and JSON are built-in, but with some extra work you can do
SOAP (search this forum for links).
If your network requires both the client and the server to be inside a firewall then no, because VPN is not currently supported. This is one difference between the Android and Blackberry platforms right now. A Blackberry device can access intranet resources and sites just as if you were sitting at your office desk.