Hmmm, I realize my question wasn’t clear at all. I found the answer by myself, but I will explain it here so that other people can find it.
Houdini uses its own 3d lut format for the display of images in “mplay”, its image viewer. The lut reads scene linear images and must do the conversion to screen display. Since the input images can range in floating point values from zero to well above 1, the lut needs a 1D shaper lut at the input to “reshape” the values between 0 and 1. Usually, we use a log shaper for that.
I made a few experiments in Nuke to test how high the sRGB ODT can read values before clipping. I used a ramp from black to float valut 50.0 in an image 5000 pixels wide. I applied the ODT to it and sampled the image using the sampler node. AT the top of the graph, when I zoomed in, I could see exactly where the ODT clips the values. I could easily calculate the highest values the ODT can display before clipping: 16.29325. Anything above that will be display as white 1.0.
So I need a shaper 1D-lut that can handle values as high as 16.3 to compress the values inside the range 0-1. The ACES OCIO config comes with multiple shapers in the Utility family. I tries several of them and did the same experiment to see how high they can go. All 48 nits shapers (LMT shaper, Log2 48 nits shaper, Dolby PQ 48 nits shaper) have the same range as the sRGB ODT (0-16.3) so any of them will do.
Here is the command to use to generate the lut
ociobakelut --inputspace ACEScg --outputspace "Output - sRGB" --shaperspace "Utility - Log2 48 nits shaper - AP1" --iconfig OpenColorIO-Configs/aces_1.0.3/config.ocio --format houdini --v ACEScg_to_ODT-sRGB_houdini.lut
And here is the lut file if anyone needs it.