Here are some notes on SSRS2008 in an integrated mode:
1. When integrating Reporting Services you will need to install the rsSharePoint.msi in order to set the configuration properties in SharePoint and use the Report Viewer.
2. Before you install it, go into Component Services and select DCom.
a. Right click IS_WamReg → Properties.
b. Open the Security tab and under custom security, add your SharePoint and Reporting Services service accounts giving them launch and activate permissions.
c. If necessary, you can also give them remote launch and remote activate permissions.
d. Reset IIS ( open command window and type iisreset )
3. Next install rsSharePoint.msi using the following command: msiexec /I yourfilepath\rsSharePoint.msi SKIPCA=1 (that is a capitol letter “i” after the “/”).
4. Switch to your %temp% directory and run the following command: rscustomaction.exe /I (again a capitol letter “i”).