Actually it is possible! When you launch karlson.exe the configuration will pop-up, there will be two options: Graphics and input. In the input tab you can change the controls. Hope this helps.
yes i know that, but when dani fully releases it, he will have to add custom keybinds because he will put the finished version on steam (which does NOT allow you to bind controlls to a game if the devs didnt put mappable keys.)