Adjust watermark settings Libreoffice Writer 4.3

Hello all. Just want to know how to adjust watermark settings in writer. The default colour is a rather distasteful bright green colour.

Also is it possible to change the angle/position of the watermark text, to make it run diagonally from the top-right corner to the bottom-left corner?

Lastly I would like to talk opacity- I would like to increase the opacity of the watermark so that it is less distracting to the eye. Is there a setting for this?

Many thanks folks!

EDIT: ON LO VERSIONS 5.4 OR LATER, A DEDICATED TOOL TO CREATE WATERMARKS WAS RELEASED

ON EARLIER VERSIONS, THE ANSWER BELOW WORKS JUST FINE.

AFAICS, the best way to have watermark is to add fontwork to a header (attached to paragraph). There is possibility to make all required rotation and opacity corrections you want.

This answer is obsolete already: LibreOffice 5.4 (released in summer 2017) includes a dedicated tool to add a watermark, where it’s possible to choose color, angle, and opacity settings.