Hi 
Welcome to Adobe ColdFusion forums . Multiple instance is a feature of Adobe ColdFusion Enterprise. So you will not be able to achieve the same in Standard Edition.
http://www.adobe.com/products/coldfusion-family/buying-guide.html
For development purpose, install CF 10 as trial which will act as Enterprise Edition for 30 days. After 30 days, CF 10 will become Developer edition and you can continue your development.
HTH
Thanks
VJ 