If you do not want to place the file on the SharePoint, you just have to place it on a network drive and add a link to the file on the site, so users will know where it is. To add the link you either need to use the content editor web part, the "Links" list, other webpart or the navigation.
Even if MDB files would be disabled you can easily allow them through the central administration (cetral administration -> operations -> locked file types (under security - second group from the top in the left column)
