It is indeed possible in the current state of the engine. It would require you to build from source and make some minor modifications to the scene capture cube component. I have tested it and confirmed it worked with a previous version, but haven’t tried it in 5.1.
The performance cost was quite heavy as it requires a second lumen scene, but it can still be useful for baking cube-maps for use in a variety of things. I would like to see it added in the same manner as the 2d capture moving forward. 2d captures also allow you to down-res the lumen scene to manage costs. I think it’s critical feature to add, as without it, manually baked environment captures will not accurately reflect the in game scene.
My engine ran stable with the above modifications, but I wouldn’t want to try and capture every frame for any real time application with it.