Well, it's pretty simple (once you read the DTD)
<exec_method type='method' name='start' exec='/usr/pkg/sbin/apachectl start' timeout_seconds='60'> <method_context> <method_environment> <envvar name="LD_LIBRARY_PATH" value="/usr/sfw/lib"/> </method_environment> </method_context> </exec_method>
Note Please don't ask me why I set LD_LIBRARY_PATH.. !