spdep: From matrix to listw

Dear colleagues,

Is there any quick way for converting from R-matrix to listw-object of style 'W'
(row-standardized)? 
I tried mat2listw but the result is style 'M' (which is not what I need).
I also wrote my own GAL-file writer and went through read.gal and nb2listw
(much to slow).

Any suggestions?

Regards,
Martin Reismann

Martin Reismann
c/o
Institut fuer Wirtschaftsgeographie und Geoinformatik
Wirtschaftsuniversitaet Wien
Nordbergstrasse 15, 4. Stock, Kern A
A-1090 Wien

EMail: Martin.Reismann at wu-wien.ac.at
Tel +43-(0)-1-31336-5720
Fax +43-(0)-1-31336-703