Aha… Its error message made me think I had to do a transmission-remote -t8 and then afterwards all subsequent commands would apply to t8.
I'm giving it a rest for a while.
I'm thinking of removing the symbolic link after it is a bit aged, but I don't know enough of the current behaviour of transmission.
I have another 1-hour cronjob that looks for AVI's or ISO's and puts them in a special folder where my xbox is looking for them. The cronjob takes care of cleaning up the names with help of another script that searches imdb. It also leaves a symbolic link to be able to continue seeding.
Another script which is published already turns the VIDEO_TS into one ISO and/or moves them in a separate folder as well. I have currently disabled the making of ISO's because they can not be played by my XBOX. I still haven't found out why, but maybe it's XBMC's fault. I will try it later with an updated version.
If you have suggestions which I find useful to incorporate, I'm open to it. I like to share, but do see it as a script to fulfill the needs I have to easily play them on my xbox. XBMC looks great BTW, especially with the latest Aeon skin and many backdrops that are available….. Too bad my old XBOX isn't capable of playing HD movies. Not even most HRHD can be played :(