First, it requires to have an installed version of wordpress

then, one installs in the wordpress installation the Flog plugin, which is a "Flash Frontend for CMS and blogs"
http://sourceforge.net/projects/flog/

In the plugin folder
silex-plugin-themes/flash-theme/silex-server/media/wp-default/theme-01

one replaces the background_theme01 Shockwave Flash Object by one's background theme created in Xtreme Web Designer and exported as .swf.

Don't have tried yet but it should work