1. Go to editor.
2. Play as OPFOR autorifleman (confirmed for him)
3. Tap ctrl twice or press m to open/close map in order to lower the weapon.
4. Walk/run forward (hold W down).
5. While running, tap RMB for optics simultaneous running+aiming.
6. Release W.
7. Tap RMB to leave optics.
8. Won't stop running, can only throw grenades.