installing tekkit classic on vanilla launcher

[mcm taged4]

Ok, so i have a mojang account and have no issue logging into the technic launcher. However my buddy just picked the game up yesterday and we went almost straight to tekkit classic. problem is with a microsoft account you cant log into technic launcher at the second. So I was wondering if maybe anyone has installed the modpack in vanilla because i know we aren't the only ones dealing with this problem, and unfortunately as the technic staff has said, for the time being there isn't a whole lot they can do to fix the problem other then just wait for microsoft to pull themselves together and stop breaking everything. But for the time being we still want to play tekkit. So my logic is that he still needs to be able to log in to be able to log on to uncracked server, so the only way to go about doing that is to mod vanilla, which i know would probably be a mega pain in the ass but on the plus side, only needs to be done once right. We are currently trying to figure it out on our side but any help would be great. thanks in advance to anyone that helps.

admin please move i am now realizing i should have put this under technic launcher instead, sorry guys. also to be clear we are looking for a work around solution for the time being

[JaariAtmc]

Tekkit Classic is impossibly hard to install on the vanilla launcher as it:

1. Requires a forge build that's not available (uses a custom forge 176 based on forge 164).

2. The custom forge has some mods added to it, likely in a specific order to prevent mod conflicts.

Tekkit Classic is essentially the worst modpack to try to put on the vanilla launcher.

You'll be looking at Hexxit minimum for it to be easier, and I have managed to use the vanilla launcher for Attack of the Bteam, so Tekkit Main or Tekkit Legends should possible too. Regardless, it took some swearing.