Buldozer (which is arma3.exe) requires steam client to run.

<steamPath>\steamapps\common\Arma 3\arma3.exe is your buldozer. Replace <SteamPath> with the full path to your Steam directory.

Object Builder, use File → Options and configure external viewer there like this:

-buldozer -window -noLand -exThreads=0 -mod= -noAsserts -nologs -profiles=P:\Buldozer -cfg=P:\Buldozer\Buldozer.cfg -name=Buldozer

Terrain Builder, use Tools → Preferences → Buldozer and configure .exe file path:

-buldozer -window -exThreads=0 -mod= -noAsserts -nologs -profiles=P:\Buldozer -cfg=P:\Buldozer\Buldozer.cfg -name=Buldozer

Please note that Object Builder has -noLand parameter while Terrain Builder does not.

To close buldozer, simply kill it with ALT-F4. Buldozer Controls Keyboard Shortcuts related to terrain editing used with Terrain Builder.

Anybody knows what -disableSteam command does? :)

See how to change Buldozer Cursor when working with terrain builder.