I downloaded the web configuration modification feature solution file, and tried to install like this:

stsadm -o addsolution -filename ManageConfigMods.wsp
stsadm -o deploysolution -name ManageConfigMods.wsp -immediate -allowGacDeployment

It seemed to work, and the link showed up in the Operations tab like it should, but when I click it (as a farm admin user), I get an Access Denied error page redirect.

Is there something special that has to be done to get it to work?