Crawl Rule for Crawling Specific Page across all the site collection under one content source

I have a MOSS 2007 web Application added to SharePoint 2010 Search Service Application Content Source, which is having 50+ Site Collections which follows same template. Every Site collection having one CustomPages Library and CustomPage.aspx. 

If search Service would like to crawl only CustomPage.aspx from all the site collection under the web application, what would be the Path or Regular expression while creating the Crawl Rule. 

i have given the path as  http://webapplication/sites/*/CustomPages/CustomPage.aspx, but this is not working. Can anyone help me out with correct path or regular expression in this case.

Thanks..