Did you:
Download gsgetfile.dll and FileDialogChanger from
http://www.geocities.co.jp/SiliconVa...upertino/2039/ (the download links are directly below (2nd or 3rd link) the names)? Did you then extract the arm versions of filedlgchg.cpl and gsgetfile.dll to \windows on your pda, and finally do Start-Settings-File Dialog Changer and check the checkbox (Exchange Standard File Dialog)?
It worked for me (X51V A06 english ROM), and a beautiful file dialog it is. I second the japanese wm5 update. :)
Edit: Sorry. Didn't check the links. Direct linking not possible