Ok - several months and a dozen attempts later I finally figured this out. Programming a 2008 Boxster to a new Chamberlain via Homelink is not impossible. At first, I thought it was an issue of Liftmaster/Chamberlain came out with a new version of rolling security codes that is not backwards compatible with older Homelink systems. It came out in late 2007 and many cars through as late as this year did not include it.
Meaning - if you have an old garage door opener, no problem. But if your opener just fried and you went to Home Depot and bought your run-of-the-mill Chamberlain recently, it will not program to your 2008 Boxster. I'm not sure what the cutoff date is. More information on it here:
FAQ's about the Homelink Repeater Kit for LiftMaster Models 8360 & 8550 | Facebook
The solution is reasonably simple, they sell a repeater and remote you simply plug into the wall the makes the opener backwards compatible. Another route is just get a compatible non-rolling code receiver and plug it in. I found the official unit with shipping for $42 from gatehouse.com and am on my way to less clutter in my ride. Got it - worked like a charm.
Then my wife pointed out to me that our 2004 Pathfinder worked with the new openers just fine. I guess it blows that theory. So I went back to the drawing board and literally did a grid-search style programming pattern. Got the Chamberlain to work - it was just ridiculously sensitive to positioning on the bumper. Where my older opener and the homelink repeater programmed at about any distance, the Chamberlain seems to need to be almost touching the bumper - but not quite - in exactly the right spot. Having even a half inch or so off it would not seem to take the code.
So sending the repeater back - seems to be working without it!