I have done this. Plug a mic into the line in on your tuner. Use the mic to pic up the signal. If you're lacking a mic, you could try a pair of headphones with a large driver (speaker) on them.
Good luck? :-)
OneShellShort, March 2010
only if either the tuner has a mic input so it picks up the sound fromt he guitars sound hols, or if the acoustic guitar is an electro acoustic so it can be plugged in to the tuner in the same way that an electric guitar would be
