How about providing something a simple as visual and auditory cues?
In his particular study they cued people to either
1. Forefoot strike
2. Decrease average vertical loading by 15% or
3.Decrease step length by 7-1/2 per cent (ie increase step frequency)
All 3 decreased eccentric knee joint work; but increased ankle joint work. Forefoot strike as well as cues to decrease average vertical loading (which would cause you to forefoot strike) increased ankle joint work. I guess that if you steal from Peter you need to pay Paul! Decreasing step length had no adverse effects.
What are you trying to accomplish? If it is decreased knee joint loading, such as in patients with patellofemoral problems, then this could be a very good thing. If you have a patient with a raging achilles tendinitis, then perhaps not.
Having someone decrease their step length (effectively increasing their cadence) can be one of the safest ways to decrease vertical loading rates.
Baggaley M, Willy RW, Meardon S. Primary and secondary effects of real-time feedback to reduce vertical loading rate during running Scand J Med Sci Sports. 2016 Mar 19. doi: 10.1111/sms.12670. [Epub ahead of print].