Sun type 6 keyboards come with a bunch of ‘extra’ keys on the left hand side. If these aren’t working for you try adding the following entries to you .Xmodmap file.
! Sun Type 6 USB PC keyboard special keys keycode 117 = SunCompose keycode 134 = SunProps keycode 140 = SunFront keycode 248 = SunCopy keycode 191 = SunOpen keycode 192 = SunPaste keycode 188 = SunCut keycode 222 = SunPowerSwitch SunPowerSwitchShift keycode 135 = SunUndo keycode 133 = SunAgain keycode 122 = SunFind keycode 232 = SunStop keycode 113 = SunAltGraph keycode 174 = SunAudioLowerVolume SunVideoLowerBrightness keycode 176 = SunAudioRaiseVolume SunVideoRaiseBrightness keycode 160 = SunAudioMute SunVideoDegauss keycode 245 = Help
Read the file with “xmodmap ~/.Xmodmap”, which you can put in your .xsession or .xinitrc or whatever you use to initialize your desktop.