Ok, I was able to configure a policer and apply it to ingress port 4/18 as follows:
set qos enable
set qos acl ip LIMIT-BACKUP-BW dscp 0 aggregate BACKUP-1mbps tcp any host 1.2.3.4
commit qos acl all
set qos policer aggregate BACKUP-1mbps rate 1000 policed-dscp erate 1000 drop burst 26 eburst 26
set qos acl map LIMIT-BACKUP-BW 4/18
This seems to work fairly well, and drops bandwidth consumption by this app close to 1 mbps.
Now, if I could just figure out how to make this time sensitive, I would be all set. Any ideas?