pcm 2.1 ipod adapter?
 

does anyone know where to find a ipod interface adapter for a boxster equipped with the pcm 2.1 system which will not require permanent modification to the vehicle?

I have not found a way to achieve this without doing a modification, any mod is reversible if you want it to be.

I have installed an iPod interface into my Boxster simply by tying into the ECU of the radio, I have an iPod adapter in the glove box and that is soldered onto the circuit board of the factory radio. I flashed the ECU with an iPod command, when I hit the number 6 button on my radio it powers up the iPod and brings up the menu onto the radio it self. It works very very well, and is fairly simple todo. No one will ever know what you have done with it.

You have an iPod adapter in the glove box of your 2001 Boxster? Did you have to replace the entire dash to get the glove box?
I'm pretty sure that reflashing the factory stereo and soldering some direct lines is a bit beyond what the OP is looking for, but I think that most of us would love to see pics, and a bit of a DIY.

I ended up purchasing the Porsche music player interface. it plugs into the antenna and is basically a fm modulator. the sound quality is not all I had hoped for, so I will be doing a bit more fiddling with it in hope of getting it to work better. the music plays through the fm radio, but the sound is a bit off.