First you will need to install the reporting services add-on for SharePoint Server 2007 if you haven't already.
Second, the web parts that will be required for SharePoint to access Report Services will need to be installed.
By default, the webparts are installed with SQL Server 2005 and are located in ..\Microsoft SQL Server\90\Tools\Reporting Services\SharePoint\RSWebParts.cab.
You will need to copy this file over to front end web server and run the following command:
stsadm.exe –o addwppack –filename “<path to file>\rswebparts.cab” -globalinstall
Finally, in order to properly get the Web Parts just installed to function on a MOSS2007 setup with Reporting Services you will need to make a change on the site's web.config file. The trust level must be changed to WSS_Medium.
<trust level="WSS_Medium" originalurl="">