The linked page explains how to install by hand. I'd like to eliminate the curl|bash. It's tricky to deploy a shell script in a terminal emulator, so it hasn't been done yet. The ability to fix bugs without making users upgrade their client has been invaluable during early beta.
Well, if all I have to do is run the script, I can just import it into my git repo (by submoduling iterm2's git repo, if they have one; if they don't, they need one just for this script), and just call it normally (with a bit of if wrapper to not execute on non-iterm2 terms).
Yes, all you have to do is source the script at https://iterm2.com/misc/${SHELL}_startup.in from your ~/.login, ~/.zshrc, ~/.bash_profile, or ~/.config/fish/config.fish as appropriate. If there's ever a major change you'll get a notification when you log in and you'll need to update it, but that hasn't happened yet.
