You can follow this diagram for how to setup inserts, you just need to follow the instructions for one insert path if all of your drive pedals will be on one insert: https://cdn.eventideaudio.com/manuals/h90/1.3.0/content/setup/two-mono-inserts.html
In the routing menu, turning Quick Knob 2 will adjust where the insert is in the signal path. You can put the insert before or after either preset, etc.
I would set up your insert path first and then decide where you want the drive to be by experimentation. It is more common to put the wah before the distortion, this way the distortion will interact with the harmonics introduced by the wah. But you may find that you like the wah after your distortion, and if the drive is in your insert path, you just need to turn Quick Knob 2 to change where your drive is.