[Seaside] How can I add my own #replacingAnchor brush with customized "window.open(...)" code?

[itsme213]

Dear incredibly helpful list ...

I would like a customzed anchor brush so the following:
    html replacingAnchor
        callback: [self foo];
        with: 'replaceMe'
generates the customized <a> below to replaces the current page in the 
history (to disable back button). The only change is a 4th TRUE parameter in 
the window.open(...):

<a onclick="window.open(this.href,'_self','',true);return false"
href="..._s=...&_k=...">replaceMe</a>

How do I do this? Can I get this effect using some options to the existing 
#anchor, or do I need a new brush?

Thanks - Sophie

I am using window.open() as described at 
http://www.w3schools.com/htmldom/met_win_open.asp.