And now I can post there with PostXING (v2).
Dare has put up a couple of tutorials on how to setup Metablog support for w.bloggar and BlogJet. Since I "borrowed" ideas from both of these fine applications, the setup for w.bloggar is nearly identical to what you need to do in PostXING v2. Sorry for those v1 folks, I don't think it'll work in that version. Maybe I can put out a patch so that v1 will work too.
I'd also like to thank Dare for being so helpful in the beta stage. He personally replied to my questions and gave insight on a couple of things that were very helpful (like the BOM thing, which may or may not be a fluke in the beta version of spaces)