From the Lights Out XML scripting sample package it appears that command does not work with iLO2
<RIBCL VERSION="2.0">
<LOGIN USER_LOGIN="adminname" PASSWORD="password">
<RIB_INFO MODE="write">
<MOD_GLOBAL_SETTINGS>
<!-- iLO 4 - 1.20 or later. -->
<!-- iLO 3 - 1.55 or later. -->
<!-- iLO 2 - None. -->
<IPMI_DCMI_OVER_LAN_ENABLED value="n"/>
</MOD_GLOBAL_SETTINGS>
</RIB_INFO>
</LOGIN>
</RIBCL>