I have this routine that I would like to have modified and I know just the very basics of lisp programming.

It's for monitoring specified sysvars while in a drawing session. What I'm wanting to do is take the routine below and set it up on a button to invoke the command. Which I am familiar with doing. Since you have to manually modify the routine as it is now for it to look at different sysvars, after clicking on the button, I would like it to ask me what variable I want monitored. Also, is there a way to set it up so that it can monitor more than one at a time? I would be interested in knowing how to go about setting it up for dialog box input. Not just at the command line.

(defun C:ALERTME ()
(setq VTFRXN (vlr-editor-reactor nil '((:VLR-sysVarChanged . VTF))))

(if (= (strcase (car CALLBACK)) (setq str "SAVETIME"))
(alert (strcat str " has been changed "))

I'm not necessarily asking for someone to modify it for me. Simply point me in the right direction or show me some examples you may have as I am trying to learn this as I go. Thanks in advance.