[Steve Tinker]

The new key(s) will have to be programmed to the Boxster security system - a dealer or a Porsche shop who has access to a PIWIS - without that you cannot start the engine. The lock / alarm / security module is located under the drivers seat which should be locatable seeing that you don't have a seat fitted.

As to the "mechanical" part of the key steering lock, I would think thats possible but if you are going to have to get new keys anyway, I would think you should kill both birds with the one stone and not try removing the steering lock.....
I'd ring round a couple of REPUTABLE Porsche independant shops local to you and get some idea of the cost / ease of replacement before you go ripping into the steering lock removal.