Dynamically Modifying the URL

I'm trying to figure out how to scrape a site with some sort of a sessionid embedded in its url path. For example:

http://www.abc.com/(fbyhzf45k12nudyhfpysps45)/jsp/user/SignOn.aspx

I wrote a script that is invoked after the file is scraped to retrieve that sessionId and save it onto a variable:

String url = scrapeableFile.getCurrentURL();
String sessionId = url.substring(url.indexOf('(')+1, url.indexOf(')'));
session.setVariable("SESSIONID", sessionId);

My question now is -- how do I use that SESSIONID value on the succeeding scrape file URL's like so:

http://www.abc.com/(~#SESSIONID#~)/jsp/user/sgonHttpHandler.aspx

Screen Scraper does not seem to be expanding the variables when inside the path. On the other hand, if I don't change the URL's of the succeeding scrapefiles, they won't work because the sessionid has already changed from the time I manually scraped it and during runtime.

Dick