SSony do a few very nice mics for minidisc I have used one and find the very good.
Otherwise a pair of condenser mics fed to the minidisc via a small mixer.
Better still if your at a session that uses a p.a. ask the chap in charge in you can plug into the tape out on the mixer desk/amp.
Lets face it whatever you use the quality is going to be better than those 50/60s field recordings we used to make! and we forgive them because of the nostalgia reward they give us.