If I have understood your question correctly, you need a mnemonic search too so the list narrows and looks up while you type.
Take a look at this type of an add-in:
EDIT: It may not be called "mnemonic" and I don't care about the semantics, I'm referring to the concept. Here is a link I've used in the past to build something very similar which is essentially "filter/search as you type". Entering text in one box that filters/searches another.
Hope this helps,