Mike,
I enclosed the base of my machine (after removing the four feet) with a rolling plywood base. Then sealed the gaps between the cabinet and the table. I then used the existing dust port on the machine to connect to the dust extractor.
Inside the machine I split the extractor pipe into two, one going to the under table blade guard the other directly into the cabinet. This allowes dust do be extracted at the blade but also from the cabinet. (You still have to clean out the cabinet every few months).
Also coverd the slit for the tilt mechanisn with a sheet of plastic attached to the rise and fall shaft. Sort of seals itself when the extractor is on but does obscure the markings. Dont use the markings as I use a digital blade guage.
Kept the extraction to the blade guard from the standard port.
You have to be carefull not to restrict to much airflow around the motor otherwise it will overheat, this came from one of the SIP engineers when I spoke to them about this. So far have had no problems.
Hope this helps
Jock