This should be acheivable. I'm new to Limewire as a coder, but as Limewire can detect identical files, the fields that make the file identifiable and unique could be re-searched at a later time, and Limewire could kick off the download as soon as a candidate was found. This would be a little along the lines of queueing and "More Sources needed".

I would be interested in incorporating (coding) this into LimeWire, only has someone already done it?