Can anyone tell me if it's possible to run a mic, from say a trumpet, through the MIcroKorg's audio input and use it to alter the sound/create some live effects?

If not a mic, then how about a line input from an electric guitar?

When I went to the shop (Tom Lee in Hong Kong) they didn't have a clue. Appreciate any help.

That is exactly what it's for . It can take a line input or if you do use a mic , just watch the level . The signal will be processed through the filter and envelope generators . Have fun .