I’m not on a 10.4 system right now but in Panther, go to OSX system prefs> keyboard & mouse > keyboard shortcuts> deselect the show/hide dock[opt-cmd-d]shortcut.
You can also scroll a little further down in that pref pane to Application shortcuts and add a new PS specific keyboard shortcut.
You could also create an action in PS7 with custom keyboard command to trigger select>modify>feather.
PSCS2 offers evenmore customizing options.
good luck