@David_Tschumperle technically yes, but only for the most part. Here’s the deal; what people said here is technically true, however here’s the catch: RawTherapee has many features that would seriously mess a HaldClut up if applied to it (such as tone mapping), and I use a lot of those in many of the presets. Also when applying a RawTherapee preset on a raw file, it works in a much wider colour gamut profile than the HaldClut supports, so a few losses are bound to occur there as well.
So to answer your question, yes it is doable for the most part, and I am planning on adding a whole bunch of cluts to my collections …eventually. But some features will definitely not work that way.
I personally would love to have RawTherapee pp3 files for most of the Film presets in G’MIC, cause I love them …especially Kodak Portra and Fujifilm 400H 
Glad you enjoy the presets though! 
I hope in the near future to get around to uploading some tutorial lessons, not so much on the topic of practically creating these, but in order to explain what combination of settings tends to work great for what given situation.