LEM requires an agent to be installed on your Windows/Linux servers in order to transmit (and also compress & encrypt) event logs to the LEM appliance. It is not possible to transmit the event logs to the LEM appliance without the agent.
Kiwi Syslog can leverage the Event Log Forwarder for Windows, however this also requires an installation on each client so may not be possible in your environment.
Could you clarify the environmental requirements? Are the port restrictions or concerns regarding resource consumption by the agent?