Claude;
Here's a thought, do you or a friend have an old mobile phone charger?, if cut it out of the plastic and take a look inside there. They don't put out that much power and are already converting the mains to DC. you may need from there to either step up or down depending on the LEDs.
I know that they probably will not be small enough to fit in the MR16's but will fit easili into an old CFL base:--)
This works for us, I play around with NiCds and even though the chargers are not built for them , almost ALL newer charger's outputs are right at 4.2 - 4.9 VDC and running 200mAh.
Some work just fine.
Hope that helps with the need for 220v conversion
Bruce S