Hi Kevin,
you are right, the GPIO of the SAM3S are 3.3V only, and are not 5V tolerant. [...] and would not recommend using it with 5V.
Thank you for confirming my observations.
If you don't want to create a board, you could just use a SIMtrace board and desolder the MCU (e.g. using hot air).
Uhmm, I would rather not mutilate an otherwise perfectly good SIMtrace board that is still usable for debugging lower-voltage phones. For the purpose of sniffing high-voltage SIM communication, I'll make my own little adapter PCB with just a SIMtrace-mimicking FPC connector, a SIM socket and some header pins - trivial really, I just need to get around and do it. I am not in any hurry, so I will get to it when I get to it, and then wait for the PCB fab...
M~