Hmmm, after trying this out for a few more days, it seems like it doesn't work after all. In most cases, from what I can tell, downloads will most often start over rather than continuing from a linked position. I believe the problem lies instead with the downloads.dat file, which must be editable in some fashion.
Anyway, sorry for any false hopes, and if anyone has a recommendation for a better linux gnutella client, I'd like to hear it.