Like you I have some applications wich read a log file outside the context (on the server)
Here I have 18 applications that read the same properties folder wich I specify as jboss startup parameter so, the application can read this path (outside the context) and read my propertie file.
so on your run.conf file $JBOSS_HOME/bin/run.conf on your JAVA_OPTS variable add a configuration pointing to a path like this: -DXYZConfigPath=$JBOSS_HOME/configs
then your login.jar have to read this configuration so it can load the propertie file from one unique place.
My english is not good, so I hope you understand