So...I've just spent quite a bit of tonight wrestling with a lack of wx support in all the Erlang versions I've built from source with kerl.
As it turns out, the biggest issue is that I needed to configure wx thusly when building:
./configure --enable-unicode --enable-debug
If you just do that right there, all will be well. I had to dig a few layers deep into actools-generated nonsense to determine this, and thought it might save someone else from a struggle later, so there you have it.
Hope it's helpful. Once you have wx built that way, all should be well with the world when your Erlang installs.