overlay key assignment

i heard that i could trigger one of the text scrolls by assigning it to a key, but i couldn't find it! i went to settings, keys, space, and i couldn't find it. help! 

The RabidHaMsTeR.Org forum
https://www.rabidhamster.org/phpBB3/
https://www.rabidhamster.org/phpBB3/viewtopic.php?f=10&t=191