Setting solr home directory in websphere

[Kevin Cunningham]

I've installed Solr a hundred times using Tomcat (on Windows) but now need to 
get it going with WebSphere (on Windows).  For whatever reason this seems to be 
black magic :)  I've installed the war file but have no idea how to set Solr 
home to let WebSphere know where the index and config files are.  Can someone 
enlighten me on how to do this please?