Garry,
If you have Mojo and change the project format from 1080i HDV to 30i, the Mojo will do a realtime downconvert and output the HDV signal out of the Mojo as a SD signal which can be viewed on any SD monitor while you edit. Of course, you will have to change the format back to 1080i HDV if you want to digitize any additional footage.
There is no way to preview true HDV (that I know of) as you edit.
I hope this helps.
George Bellias
Jade Productions