Just curious, what is a headlock? 

Would this be similar to a headgate?

If so, then yes, some horned animals can be worked using a headgate.  Probably won't be any possibility of using an automatic headgate though, almost definitely needs to be manually operated. 

Longhorns, probably not, but something along the lines of a Horned Hereford, yes, just have to have someone that knows what they're doing running the headgate. 

And the cattle will need to be gentle to start with.  If they are going to be hitting the headgate at full speed, the chance of catching horned cattle at high speed is very slim.

If a headlock is something different than a headgate, enlighten me, 

... and ignore the above opinions.