1) Simply edit the script to show a different line. The script is dead easy (even for those who don't know much about programming). The only line you should change is
code:
var OnlineTime = "Online Time: " + Sec + " Seconds " + Min + " Minutes " + Hrs + " Hours " + Days + " Days";
to
code:
var OnlineTime = "Online Time: " + Days + " Days " + Hrs + " Hours " + Min + " Minutes " + Sec + " Seconds";
2) Note that the script is poorly written. I would actually not suggest to use it in its current form as it doesn't take in account singular values, doesn't take in account flood limits, constantly needs JScript to change the type of variables (string and numbers are mixed), you can't turn it off, etc, etc...
3) The script is very very highly annoying to all your contacts since it changes your personal message every second; be prepared to get banned from your contacts' contactlists when you use it.
EDIT: I need to refresh before I reply