Look at the photos. See those holes in the corners with solder on them ? See the IN+/IN- and OUT+/OUT- ?
See the little blue trimpot for adjusting the voltage ? You can get some brass hardware and ring terminals and you're good to go.
Don't use any non-brass hardware. (trust me. I'm a professional).
I guess I don't have to tell you to adjust the voltage to 6V BEFORE connecting the servo, right ? (the converters are shipped with the output pre-adjusted to 20V) That would be bad.... =(
FYI- FOR $5 , I WOULD GET THE 5A BECAUSE THE INDUCTOR IS LARGER AND IT HAS A HEATSINK