Both the ESCAPE and ` keys are defined as META1 control key, so if you do not have ESC you can use `. To obtain a ` you must type ` twice. If you type ESCAPE twice you'll get the ircII command completion function instead.
This script is provided for those, who switch terminals very often and some terminals don't have ESC in the left upper corner. The "`" which in those cases usually is there instead of ESC will then act as META1, too.