No, when I say malt, I mean malted barley. I know that's where DME comes from of course, which is why it seems like you should just be able to use that instead of DME.
As for where to leave the jar, I have read that organic ingredients (honey, fruit) has yeast on it already. Making a starter with honey, for example, I read that you just have to mix it up and wait. Same for making a bread starter. Wouldn't that also work with malted barley? Or has the malting process eliminated whatever yeast might have been there?