You can set your CTM in Interface Options - Mouse Options.
You can also toggle it on/off in game with a console command (0 = off, 1 = on): /Console AutoInteract 1

For my caster teams, I have CTM enabled for the slaves and disabled for the main, automatically on every switch. So I don't have the leader move about when I click the ground by mistake trying to get an NPC targeted. But so my slaves will auto run to a quest guy if out of range.

For my melee teams, I leave CTM enabled on everyone all of the time. Basically so it is enabled for melee IWT spam/selective pressing always.

You can set IS Boxer to enable CTM when you press your IWT key, and to disable it as soon as you release your IWT key. I would personally want a mapped key, with an easier keybind than Alt J, but if that works for you then all is good.

Mapped Key: IWT
Hotkey: G1 (or whatever)
Step 1:
- Keystroke Actions > Warcraft macro action > /Console AutoInteract 1
- Send IWT keybind to Warcraft
Step 2:
- Keystroke Actions > Warcraft macro action > /Console AutoInteract 0
Set it to advance a step on press or release.