I asked Native Instruments about this and this is their reply:
Kontakt Player 2.2.3 does work within Logic 8 on either Power PC and Intel based Macs. You can use different output configuration which are now pre-assigned by Logic directly: e.g. stereo, 8 x stereo, 8 x mono etc....Hope this helps,
We always recommend to use one of the pre-assigned settings of Logic and select the same output configuration within the Kontakt Player 2 channel mixer.
So basically, what users should do is to start up KP2 in standalone mode, then set up their channel output configurations - e.g. 8 x stereo -> which means create 8 stereo channels in the KP2 mixer, assign the outputs, then press "make default".
After pressing "make default" a message pops up which says to restart KP2 to make the changes active (close and re-open all instances).
When you have done this, please start up Logic Pro 8 again and load up the appropriate output coniguration from KP2 on your AU instrument track: e.g. 8 x stereo/ 8 x mono.
Now, load up the instruments from GPO or JABB and set up the plug-in outputs /channels for the different instruments. The KP2 outputs will appear as available inputs on AUX tracks in the Logic Pro mixer. Note that stereo plug-in outputs do only appear on stereo AUX tracks. Mono plug-in outs do only appear on mono AUX objects.