Are you doing this to save disk space or for automation to blow out the agent to a large number of machines?
If for disk space, create a .hq directory and agent.properties in the user home of whoevers going to run the agent.
~/.hq/agent.properties
agent.logDir=~/hyperic/agent/logs/
agent.dataDir=~/hyperic/agent/data/
agent.tmpDir=~/hyperic/agent/tmp/
Note that this is not in the documentation as it hasnt been tested by Hyperic QA yet so its officially "unsupported".
Also, you'll probably triple youre network I/O doing things with what you have below just on metric data alone. Not to mention the agents write a pretty generous log file.
let me know what you think.