Change encoding of file names in Wdired

[Marcin Borkowski <mbork@wmi.amu.edu.pl>]

Hi all Emacs Gurus,

I have a directory ("folder" in newspeak;)) with a few files.  The
names of these files include non-ASCII letters (more precisely: Polish
letters with diacritical signs, like ąćę.txt (fictional example)).  I
want them to be renamed to ace.txt etc.  I imagined that I could do
something like

C-x d DIR
C-x C-q
<something cool>
C-c C-c

What should I substitute for <something cool>?

C-x h
M-x encode-coding-region us-ascii

is pretty close, but converts non-ASCII characters to question marks,
which is not exactly what I want.

Of course, I could write a simple Elisp function, performing 18
substitutions (there are 9 non-ASCII letters in the Polish alphabet),
but I suspect that something like this exists already.  This is Emacs,
after all;).

TIA,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Adam Mickiewicz University