Actually you can use any flash menu with any theme on your phone. You just have to unpack the thm file, by renaming it to tar and then extract it using winrar for example.
There should be some kind of xml -file in the archive. Open it with wordpad and edit it like that:
<?xml version="1.0"?>
<!-- Created with Sony Ericsson Themes Creator -->
<Sony_Ericsson_theme version="4.5">
<Desktop_style Type="File" Source="grouped_desktop.swf"/>
<Author_firstname value="Human Interface Design"/>
<Author_lastname value="Creative Design Center"/>
<Author_organisation value="Sony Ericsson"/>
While grouped_desktop.swf is the name of the flash file. Change it to the name of the flash menu you want to use.
Hope I could help.