DL.3 content video content preparation using current software

I have used High End DL.3 projection units that require very specific (old format) video content preparation. The requirements are as follows: 1024x768 pixels, constant bit rate (18,000 to 20,000 bps), 29.97 fps (24 fps, 25 fps or 29.97 or 30 fps are listed), closed GOP structure requiring all "I" frames, elementary stream with no audio, progressive frame file and a 4:2:0 colorspace.

The server contained in the unit rejects virtually anything that is not encoded as above. I have been able to come quite close to the above specifications when producing an m2v file using an older version of Squeeze (Sorenson Squeeze 8). The DL.3 server accepts the video but always gives a warning that the content is not all "I" frame.

Does anyone know of conversion software that can meet all of the above specifications (yes...I know this is somewhat old stuff) for a Mac (I would be glad to run Windows programs if that is what it takes)?

High End (Barco) has referenced some specific software but it seems none of this is currently available.