Haven't seen a Tutorial about this yet,
To prevent your unit from turning if you use a WSAD like movemtn for your unit, so it actually strafes you can simply set their Turning Rate on the Unit in Unit-DataEditor to 0.
To still be able to turn them around you could add QE to Make the Unit face an specific angle.
Go into your Data Editor
Choose unit you want to strafe
Change Turning Rate attribute to 0 (stationary is not required as in screenshot shown)
this will fix the Unit view to the default Angle (so you set ie angle to 90° by default in editor)
so your unit will look upward all the time