Switch Track Mayhem
Hi!
As long as on the merge side of the switch you have a straight section that can fit a whole train (aka you can sneak a transfer track in there), you can use my Custom switch track tutorial post as a reference.
The changes you'd need with respect to that tutorial would be that you'd need to create a third 3d track piece and that your hidden transfer track would have 3 positions instead of 2, but it's definitely doable.
I haven't worked much with custom block setup because I like the custom script approach more, but either way, after you have done all the visual work, you just need to make sure that your hidden transfer track is in the correct position for each of the possibilities of the switch and for the one exit on the other side of the switch and that you animate the 3d track pieces accordingly.
In any case, is your "certain Intamin Accelerator" by any chance Drayton Manor's Gold Rush? Out of the top of my head, it's the only one I can think of that matches your description.
U can make a custom script using ScriptGenerator from MusicKid43's
Thank you guys so much for the help. And to answer your question: it is the now defunct Kingda Ka at Six Flags Great Adventure.
Oh, ok, so I guess you're reimagining it quite a lot, because you really threw me off with the 3 way switch and multipass launch.
Anyway, good luck with the project, and if you follow tutorial and need any help feel free to comment there!

I have just recently gone in depth into NoLimits2 and am trying to make a reimagined version of a certain Intamin Accelerator. I was wondering if anyone that is a scripting god could help me make a 3 way merge track to work with the multipass launch. (Currently using custom block setup to get the trains rolling.)