We have updated the TechnicClient which will ask you to update the next time you hit "Play" as well as the MultiMC pack!
https://pastebin.com/ipb1SdxnAll the instructions are in here, as well as the manual installation; if you already have MultiMC and do not want to download the full version, here is the mod:
https://mega.nz/file/riRFGIzR#jVkmlOhmM0dQCRKlUavqWK1YKljcp96vQUGYYbnNOxY