> Hi, new user here.  Is it possible to setup a
> seperate location from the mirrored website to
> download large files that I have already locally?
Nope. 

HTT only knows about the URLs/files it has in its cache. Only when it
encounters a previous known one does it check the mirror for the file and
redownload if missing (or not if "do not re-download locally erased
files=checked")

Even if you put the files where they would be downloaded, with the exact name,
HTT already knows it's a new file (not in cache) and download loads it.

You can filter out very large files (-*[> 10000000]) and then change the links
to them in the html to point to your files. But you'll have to do that every
time you update the mirror.