All the message says is "To open the basement, pull three switches. But be careful, four of them are wrong" or something to that extent. I'm uploading a new version now with a more helpful hint. It'll still require some thinking, but the answer MAKES sense.
Now for those of you who want to cheat, there is a picture in the Picture folder with the correct numbering of the switches. The problem is there are four pictures and only one is correct. So if you want to try to cheat, you'll have to guess which map is correct.
That said, if you go to the wall above where the growl triggers, it will display a hint. You can view it as many times as you want.
*edit- this all refers to the version I'm about to upload, one moment.
BETA V4.21 -
http://www.megaupload.com/?d=J3Z82QR4
If everyone likes this way of displaying a picture, I'll make maps for the tower floors that you can use to help you navigate them.
More Hints- The sign gives you a riddle which tells you the order to pull the switches (the three correct switches must also be pulled in the correct order). The map shows you where those switches are.
I'd recommend just using the in-game picture, but if you really want to know. Go to the "Pictures" folder under Graphics and look for Map 1, Map 2, Map 3, and Map 4.
Really, if you can solve it, the in-game picture is way more specific as it tells you which three and in conjunction with the riddle tells you the order to pull them.