[Xastir] Xastir and WMS tiles

[Andrew Errington]

Hi,

How do I get xastir to use WMS maps?

According to the wiki, it is supported:

http://www.xastir.org/wiki/Major_Features

But, how do I specify the WMS server, and make xastir fetch the tiles?  
There's nothing in the wiki, and Google isn't showing much either.

Thanks