Both the D8R and D4R telemetry pins works the same. The only difference is that the D8R has a few extra pins since its bigger. So you have two Analogue pins whereas the D4R only has one.
The two images below show the pinouts for the D4R and D8R receivers.
So all you will need to do is change the white connector (or solder) to a regular 3 pin servo connector and make sure the green wire goes to the RX pin on the D8R, the red wire should go to the TX pin on your D8R and lastly the ground should go to the top G pin (ground) on the D8R.
Here is a photo of the D4R connected to pixhawk so you know what the colours mean.
Hope that helps