ProxyPass / balancer://mycluster can't work in mod_cluster

It is not possible to use ProxyPass / balancer://mycluster in mod_cluster.
The idea is have something like:
Listen localhost:6667
<VirtualHost localhost:6667>
ProxyPass / balancer://mycluster1/
</VirtualHost>

Listen localhost:6668
<VirtualHost localhost:6668>
ProxyPass / balancer://mycluster2/
</VirtualHost>