Although XBoard and WinBoard share the back-end code, which implements the game rules, Chu Shogi also needed new front-end support, because of the extraordinary large number of piece types. The picture above only shows the unpromoted pieces present in the initial setup, but virtually all of those promote to yet another type. So many piece images had to be added to XBoard to make Chu possible. I did not do that for WinBoard. This is why the regular edition of WinBoard doesn't support Chu.
However, there exists a fork of WinBoard, the so-called Alien Edition, which already for some years supports large Shogi variants,including Chu. It doesn't use the same pictogram representation of pieces like in the image posted above, though, but uses (depending on the board size you select), either the 'mnemonic piece set' or bare kanji representation (and in one size even fully drawn Shogi tiles). This is why I didn't bother with the regular edition of WinBoard.
See:
http://hgm.nubati.net/ShogiVars.htmlhttp://forum.81squareuniverse.com/viewt ... =18&t=1409