R help - Oct 2007 - adjust labels in plot:terminal_panel {party}

Hi List,

I am unsuccessfully trying to beautify barplot outputs from ctree. For
example I would like to  rotate x-axis lables and resize/change
font/type.

mtree <- ctree(ME ~ ., data = mammoexp)
plot(mtree,terminal_panel=node_barplot(mtree,col="black",fill=NULL,
        beside=TRUE, ylines=NULL, widths=1,gap=NULL,
reverse=FALSE,id=FALSE))

plot(mtree,terminal_panel=node_barplot(mtree,col="black",fill=NULL,
        beside=TRUE, ylines=NULL, widths=1,gap=NULL,
        reverse=FALSE,id=FALSE, gp_labels=gpar(fontsize=20,
rot_labels=90)
                                       )
)

Any help appreciated

Thanks 
Herry