McDarren - I realise you've got most of this working already. You're saying that you're trying to abstract the keyword-lookup. I've done something very similar, and posted it here. In your case, you want to change the delimiters, but I think it can be used as a framework for a very good generic-lookup-and-then-modify tool. In fact, I use this code in production.

Just create an expand_var function, and use that to do lookups.