I know this is a closed issue, but I'd like to mention how awkward the solution on the wiki is... It's very non obvious. What I discovered was that if I define the properties within a <core/> in solr.xml, they pass all the way to my dih config file! Awesome. But if I define them at the <solr/> level, then they do NOT pass all the way. However, if I do the workaround, then it works. But again, that is very awkward.
Seems like if I define them at any level, they should pass all the way through.