Sun’s Application Server is based on Tomcat, but it is a modified version. To be able to use JBuilder2005 with Sun AS, you need to download the latest update for JBuilder (registered users only) from the Borland site. Via Enterprise->Configure Servers you can then select and configure a “Sun 8.x+” server.
Perhaps I’m not enlightened here, but in the configuration dialog is an entry for the path to the serversoftware (in this case “SunAppserver”). This needs to be locally accessible, so I needed to map a drive to my server, since that’s where the AS is running. Why is that? What has deployment to an AS to do with paths and drives? Isn’t that why we wanted an AS in the first place: easier (single point of) deployment?