Last year I had posted some powershell scripts to update the config files when installing multiple instances. I have update the scripts today to be compatible with R2.
As usual, open up the scripts in notepad or powershell editor. Change the path of the instance and now there is a version number.
Update the bold highlighted text in the script.
$version = "188.8.131.52"
$webConfig = "C:\Program Files\Microsoft SQL Server\MSRS10_50.ANDROMEDA\Reporting Services\ReportServer\rssrvpolicy.config"
Should save you both time and making errors.
The scripts are located here: