Not on this page. But you could use the configurable applet page that the Piececlopedia links to, and write the Betza move you want in the URL.
I wanted to try out the Blue Gecko (frB4lbW2flFbrFfW) but I can't limit the B move to 4 on this diagram.
I guess I should extend the move-definition aid to 11x11 one of these days. But in case of the Blue Gecko, why bother? The 4th step of the B move will hardly ever be needed. And even when you leave out the frB move altogether, it can already force checkmate. You could also use B3 plus a direct AY leap, which shows that adding the AY leap does not shorten the mate (on 8x8, at least).
Not on this page. But you could use the configurable applet page that the Piececlopedia links to, and write the Betza move you want in the URL.
I guess I should extend the move-definition aid to 11x11 one of these days. But in case of the Blue Gecko, why bother? The 4th step of the B move will hardly ever be needed. And even when you leave out the frB move altogether, it can already force checkmate. You could also use B3 plus a direct AY leap, which shows that adding the AY leap does not shorten the mate (on 8x8, at least).