It sounds to me like you're trying to make a cable from the 25 pin beau plug on the monitor shelf to a VGA connector that plugs into the back of a LCD display? The CLK and SDA lines are not needed or used. The drawing I posted is for a CRT and J340 is the beau plug on the back of the monitor. On the P340 side from the machine end those two signals are not even connected to pins 10 and 11.
To make an adapter you need to use the red, green, blue, horz sync, vert sync, a ground. That's all you need for the video signals. Here's a VGA connector pinout I grabbed from google. Make sure you look at the tiny numbers next to the pins and get the wires connected to the right ones.
Hope that helps.