This is the one for plist:
<dict>
<key>cell</key>
<string>PSSwitchCell</string> //This is the switch to turn the slider on or off
<key>default</key>
<false/>
<key>defaults</key>
<string>xxxx</string>
<key>key</key>
<string>kKEY</string>
<key>label</key>
<string>SWITCH NAME</string>
</dict>
<dict>
<key>cell</key>
<string>PSSliderCell</string>
<key>default</key>
<integer>1</integer>
<key>defaults</key>
<string>xxxx</string>
<key>key</key>
<string>kkey</string>
<key>label</key>
<string>Modifier</string>
<key>max</key>
<real>100</real>
<key>min</key>
<real>1</real>
<key>showValue</key>
<false/>
<key>alignment</key>
<string>3</string>
</dict>
Take a look at this also: http://iphonedevwiki.net/index.php/Preferences_specifier_plist#PSSliderCell