In the first step before launching the program, the ext2fs partition which contains the deleted file must be remounted to read-only. Please refer to HOWTO/min/Ext2fs-Undeletion for details.
To launch channel16, you must login as root and do the following:
channel16 -d deviceDevice is the device file containing the deleted inodes (e.g. /dev/hda1). Diagram 1 shows the front end of channel16.