In FCP, the Audio/Video Sequence Preset setting you will need for MXF is either IMX 50 (NTSC or PAL). You can also select the Sequence in the browser and Control Click and select Settings, you'll see a Sequence Settings window. There will be an area called QuickTime Video Settings and then Compressor: with a pull down menu. That menu will allow you to choose IMX50, IMX40 and IMX30. In theory one SHOULD be able to create an IMX50, IMX40 or IMX30 custom sequence (if the source is with that compression rate) without rendering.