The UK site has a very long thread on this topic … the short version is this is not going to happen. Huel is so different from Keto that they would have to make something completely different. I tried a couple of the hacks and failed badly but even those are not Keto … or even Keto 'ish.
If you want a Keto meal replacement shake I would point you to Keto Chow … this is some seriously amazing stuff. These products are mixed with a liquid fat … typically a heavy cream (heavy whipping cream in the US) or an oil (usually avocado oil), plus some water.