I guess it depends on how well SWT can absorb native components. Probably it should be easier than in case of AWT/Swing[1]. In any case you need to modify the dukescript-presenters codebase - as far as I see there is no FXBrowsers-like wrapper and you'd need to get on hold of the native component hidden behind Fn.Presenter somehow...
I guess the work will require insight into the dukescript-presenters codebase as well as SWT which is something I don't have.
-jt
[1] For example using java.awt.Desktop and the native presenter on Linux crashes the VM as the presenter requires GTK3.0+ and AWT is written against GTK2.0.