Data Display Expresion AEL files have to be loaded through a file called user_defined_fun.ael. This file can then contain load expressions to load other user define AEL files, i.e. "load("more_user_defined_fun.ael");".
The easiest/quickest way to get the files loaded is then to copy all of the files, user_defined_fun.ael and all the files that it loads into $HOME/hpeesof/expressions/ael and restart ADS. The expressions will then get loaded when the Data Display is opened.