Best scroller! (HELP!)

Hello guys!

First of all, sorry for my english...

I have a "little" BIG problem. I found an excellent tutorial about "scrollers in SwishMax" under this link:
http://www.13dots.com/forum/index.php?showtopic=8340

I followed Mr. DPC's instructions and everything works well, but there is still one thing that's difficult and irritating. Each time I add new contents to the scrollable sprite, I have to reenter the right values which are different from time to time and VERY hard to figure out.

So I need a method to set the TOP and BOTTOM values but I don't know how... I am not an expert, please help! This scrollbar is awesome. This is the only problem I have. I cannot contact with the author because the forum is shut down.

I enclose the SWI file. If someone can edit it and send it to me, I would be really happy!

I am using SwishMax 1 (Build: 2007.05.24)

Thank you very much for your kind help!