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 ()
(vl-load-com)
(setq VTFRXN (vlr-editor-reactor nil '((:VLR-sysVarChanged . VTF))))
)

(defun VTF (CALL CALLBACK)
(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.