Search pedals on the forum and you can read all the troubles people have had. The brake pedal is the worst. Used soapy hot water and a heat gun and still took an hour.
Used WD-40, a hair dryer and a stubby screwdriver for the brake pedal. It took about 15 minutes. I got 2 sides on, then used the screwdriver to reach behind and "flip" bits at a time into place.
The gas pedal was a surprise. I was expecting it to snap right into place using my hands. It would not go. So I got the clips on the one side lined up and the "hollow" positioned over the original plastic pedal (it is a tight fit - alignment). Then I got into the driver's seat and pressed down hard with my foot until it clicked into place. Thought I was going to break something, but it fit perfectly.
It would have been easier if you didnt use the water, i think it even says not to use soapy water in the WK1 pedal instructions. Mine were a bitch to install as well. They looks great though:thumbsup:
Here's the thread for the emergency brake pedal. There are three different methods shown if you read all the posts. Not too hard, once you get the Mercedes pedal cover (about $25 in my area).