Partitioning in the installer

I'm working on updates and am very close to getting something that at least runs. However, the installer doesn't support more than three partitions, so I have to create the others manually. Where would the best place to address this be? I'm not sure if this needs a patch to the installer's C source code, or if I should fix it in a script somewhere. -- Sincerely, Demi Marie Obenour (she/her/hers)