Add a torrent to Transmission with the download directory set to the torrents parent directory. This might not work as intended if Transmission already keeps track of the torrent to be added or for any other reason.

transbtadd.py

#!/usr/bin/env python
# 2013 CC0 http://creativecommons.org/publicdomain/zero/1.0/
import os.path, sys, transmissionrpc
tc = transmissionrpc.Client()
for torrent in map(os.path.abspath, sys.argv[1:]) :
	try : tc.add_torrent(torrent, download_dir = os.path.dirname(torrent))
	except : print ("Failed adding {0:s}".format(torrent))