ATmega328 5v to 3.3v, how to?

Hey guys,

I'm having a hard time trying to understand how to operate an ATmega328 at 3.3v...
I couldn't find a topic discussing this. The search field isn't helping much.

Do you know what I would need?

- Can I use an ATmega328 at 3.3v with the default Arduino Uno optiboot?

- Do I need any additional components, besides the crystal and capacitors? Ideally I'd prefer to use the internal resonator, even sacrificing speed, but it seems to involve changing the bootloader and setting fuses, which I don't understand at all.

- Will the FTDI cable that I bought from the emon store, work directly on the microcontroller at 3.3v with no modifications? If so, what would the wiring be like, between the FTDI and the ATmega328 pins? If not, what modifications must I do for it to operate correctly at this voltage?

- Also, and this is somewhat important, can I use any ATmega328 preloaded with the Uno optiboot, on any of the emon modules? I mean are there any differences in the bootloader, or fuses...?

I thought it made sense to ask here since all of the emon modules seem to run on 3.3v.
That being said, there must be someone around here who knows exactly what to do :)

Thanks in advance for your time.