If you don't want run an onerous asp file at all on the new site, you can do a custom 404 on the web server. If you point the 404 page to a .cfm file, you can extract all the various features from the request by including:
<!--- parse out the text in the URL parameters into an array --->
<cfset variables.requestparams = listtoarray(cgi.query_string,'/?&')>
<!--- get rid of the first 2 items in the array since they dont represent request info --->
<cfset foo = arraydeleteat(variables.requestparams,1)>
<cfset foo = arraydeleteat(variables.requestparams,1)>
You'll be left with an array representing the parameters that were passed in the original request. You can follow up on this by doing whatever analysis you need to on the url components to map it against the analogous pages in your CF site.