General tab is now Settings and
Desktop is now called Custom.
If that is what you mean.
Yes there is an option called custom,
but if I choose it, I still can´t change
the codec. I want to use dnxHD,
which i can in After Effects with Quicktime.
All I can choose is I-Frame Mpeg, DvcProHD and
Microsoft Avi. But i can´t configure any of this codecs.
These are the only codec you can choose for a render format and they are not configurable. DV and DVCProHD are fixed formats which you could not change even if Adobe let you. Theoretically you could the datarate of MPEG I frame but Adobe do not give you this option. If you add a device like a Matrox MX02 then you also get the Matrox codec which you can configure, but you cannot simply choose any codec you would like. I am sure I have seen a feature request to add this ability somewhere but it would not hurt to add one yourself.
The codecs you mention are just for preview.