The only way that I know of, is that in steam you can go back to prevous stable version. Don't know if there is a way to do it if you've bought it on their website. WaveFunctionP have made an update to KSPI, so that it works on 24.1, yet there are a lot of bugs. The same goes with B9, you can get it to work, but it is not balanced balanced, and it's technically not updated for the current version of KSP.