Wireless broadband - IP and DNS issues

I am using a wireles broadband service connected to a linksys router (which has dynamic dns options.) which in turn is connected to a ethernet enabled data collection terminal. This terminal is equipped with an embedded web server.

With this setup I have  a portable data collection device that can be "polled" accross the web via web browser and, of course, the router keeps the dynamic dns servcie updated with its frequently changing IP.

I have one issue.  I have some ancillary software which can connect to this device via it's IP address but not it's domain address...(its actually a field length issue but regardless of that annoyingly simple thing it can't be changed at the moment)

The following background information may be of some use. At my office I run a Microsoft SBS Server connected via a ADSL broadband router to the rest of the world. The router points to my service providers dns's

Now..I only have a limited understanding here but I know what I want to achieve so I am thinking that perhaps I can point my software to an IP on my local network and get my Microsoft SBS DNS to resolve that loal addreess to the dynamic dns service that I am using?

I am on the right track? If so how do I make the entries in SBS's DNS Records