Here is a method for a simplified throttle cable on the om606. It may work for other motors (I suspect the om605, om604)
https://www.youtube.com/watch?v=DDr96CfzNL8
Part 2
https://www.youtube.com/watch?v=AohBSUHAhlE
This was made for a better pedal feel, and I swapped a turbo block with a mechanical pump. As a result of the diffferent intake manifold I had to mock something up anyways, the real plus for me was that the pedal feel is much better.