I just finished the install of a Bergwerks keyless entry system on my 89 300TE.
After searching the forum and the web, Bergwerks was the one place that sold a complete DIY kit.
Carl from Bergwerks sent me all the info I needed before I bought the unit and I decided that it was an easy DIY project.
The system arrived and it turned out to be a "Your Valet" model 710T by directed electronics.
The necessary modules were included, headlight/horn blinker/honker, the dome light relay, and the door relay module. It had already been programmed for the 3.5 pulse as needed by the Mercedes system.
The instructions were clear, the green wire that is in the door jam is a pain to find and there are several wire harnesses you need to look in. Don't give up it's there, I gave up and used the green wire at the alarm module, only to find it would unlock but not lock, so I went digging to find the wire in the jam.
I was VERY impressed by the fact that the factory wire harnesses are individually sealed. Most harnesses I've seen are just taped into one big bundle.
I only have 2 complaints about the keyless system, the key fob transmitter is a bit cheap looking, and the dome light module stays on for its time limit even after the car is started.
I have asked Carl about both these problems and I hope to hear back with a solution.
The Valet, while cheap looking has a lot of features, and I am sure I will be able to solve my issues.