In Torchlight 2 what are the keyboard shortcut keys for players who don't have a scrolling mouse wheel (or in my case one who uses a pen and tablet instead of a mouse).
TL;DR: - to zoom out = to zoom in, but these can be edited with the below steps
A quick check of the steam forums says the - key will zoom out and the = will zoom in.
There should be a "Controls" menu under Options that will let you re-assign functions to other keys. There should be an option to change zoom from mouse wheel to whatever you would like.
If that doesn't work for you, someone on the Steam Community wrote an entire guide for editing your settings.txt file to create the customization you want:
In particular you would be looking for the definitions of the variables and the definitions of the hotkeys. There it will tell you what you will want to change and what number the key you're interested in is.
For example, if you wanted to use this method to re-assign zoom in to Page Up, you would change settings.txt so that KEYMAP_ZOOMIN :187 read as KEYMAP_ZOOMIN :33.