Hi Severin,
Right now we are in the process of fixing it. Currently the only way to do it is if you have a dedicated HANA and OS Access to it, and it involves breaking SAML Trusts that you have established with this Hana (as you modify it's SP configuration)
If you are fine with this - let me know and i will send you the guide.
If not - I expect that the development of the feature will complete by the end of February. Which means that by mid of March it will be available on the HCP Factory Landscapes
Regards, Vladimir