i've managed to change the maximum number of running torrents in CTorrent on my my book white edition.
enable SSH via the advanced options
get psftp.exe and connect to your mybook with the user root and password welc0me
use the following command to change directories "cd /proto/SxM_webui/ctcs"
transfer the config file to your computer with "get bt_ctcsconfig.inc"
(it gets downloaded into the same folder as psftp.exe)
edit this file with a program like notepad and change the value that behind "$max_running_tasks = " (default is 3)
(save the file and close it)
go back to psftp and type "put bt_ctcsconfig.inc" to transfer the modified file back to your my book
then type exit to close psftp
reboot your my book for the changes to take effect