Stoneys,
Its very easy for you to do...
go to data > cfg > commands.cfg
open it up with note pad.
look for this entry
[Cmd261]
Name=Report_weather
Contexts=1
MnID=0x3F250006
and make it look like this
[Cmd261]
Name=Report_weather
Contexts=1
MnID=0x3F250006
Key0=0x57,s,"Shift+W"
this will now get you weather by hitting shift+w
in the future you can use this utility to discover key mappings for any key and key combo, then input that map into the config file and your good to go...
Use this little tool developed by Timetraveler for SH3.
http://www.filefront.com/15784615/SH3KeyChecker.zip/