[flash mx] aarg how to stop infinite menue

I would really need help regarding the INFINITE MENUE TUTORIAL here on kirupa (http://www.kirupa.com/developer/mx/infinite.htm)!!!

It uses this script:

onClipEvent (load)
{
xcenter=150;
speed=1/10;
}
onClipEvent (enterFrame)
{
var distance=_root._xmouse-xcenter;
_x+=(distance*speed);
if (_x > 0) _x=-300;
if (_x < -300) _x=0;
}

[COLOR=fuchsia]I would like to know what i will have to change in order to:[/COLOR]

[COLOR=blue]1.[/COLOR] Make the MC stop in the middle area of the movie, for example x=300 till X= 500, and NOT just x=0.

[COLOR=seagreen]2.[/COLOR] Make the MC scroll the other way around! => if i move the courser to the left side the movie should scroll to the right.

I uploaded a swf to make it (hopefully) more clearer!
www.bware-design.de/FlurTest.swf

[SIZE=1]Just in case somebody is interested, this is part of my diploma (i will be majoring in interior design) and the goal is that the user will be able to walk through my selfmade house in order to learn about keeping things in order. Therefore it be nicer for the user if he can stop the movement of the room in a wider area and it be more logical if the movement works the other way around. (The problem is just that i learn Flash by try and error and all by my self, so the things i tried with this script all didnt work out. snif.)
[/SIZE]
[SIZE=1][SIZE=2]
full of hopes awaiting your wisdom
TheCuteness
[/SIZE][/SIZE]