generate unique url with url-rewriting.

want to generate a url somthing like this
Ex: http://forums.asp.net/t/1662266.aspx/1?Modal+Popup#
 
now on the above url you can see after .aspx page they have added /1??Modal+Popup#
this subject line as a url
can any one help me how i can achieve it ,
i know there is a tech of url rewriting , i also search more on net also but not getting any simple way to simple code
can any one asist me, i dnt want that ISAPI re-write and all that coz i need to install this with IIS
i dnt want to do with IIS only with the CODE can any one plz help me out
 
 
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