SCOM 2007 R2 Manually installed agents

Sometimes it is needed to change status of manually installed agents in SCOM. 
This change(to "automatically installed") gives possibilities to auto-update agents in future, repair, uninstall and to change/add management server/failover server.

Set agent proxy enabled for all agents in SCOM

Some customers prefer to enable agent proxy on all agents.

There are 2 possible solutions in this case:
- running powershell script by schedule, which will set agent proxy enabled
- configure default global setting to make all new agents proxy enabled