Using custom (dark) L&F in IDEA 9

I've been thinking of using some dark L&F in IDEA 9.

I've found Substance (https://substance.dev.java.net/) to be looking quite nice.
And have tried to "install" it by putting corresponding JARs (substance.jar + trident.jar) into IDEA/lib folder.
I've also updated substance.jar to include appropriate META-INF\services\javax.swing.LookAndFeel - to make the L&F discoverable.
But that did not help - IDEA did not show it in Appearance settings.

Then I tried to "enforce" it with -Dswing.defaultlaf=org.pushingpixels.substance.api.skin.SubstanceTwilightLookAndFeel and got the following error message in idea.log
2010-07-22 13:27:42,762 [    454]  ERROR - llij.ide.plugins.PluginManager - Cannot load org.pushingpixels.substance.api.skin.SubstanceTwilightLookAndFeel
java.lang.Error: Cannot load org.pushingpixels.substance.api.skin.SubstanceTwilightLookAndFeel
at javax.swing.UIManager.initializeDefaultLAF(UIManager.java:1319)
at javax.swing.UIManager.initialize(UIManager.java:1406)
...

Then I found some similar topics on this forum. But those are quite outdated (the most recent I could find is 2008).
Instruction from this topic http://devnet.jetbrains.net/message/4899738 helped to get Substance L&F into IDEA's list of choices.
However trying to apply it just reports an error.

The questions are:
- Is it still possible to use custom L&F with IDEA 9+ ?
- What is the most appropriate way to set it up?
- What is the problem with Substance L&F, why cannot it be loaded? (I run IDEA on WinXP and Java 1.6.0_21)
- Is there any other good-looking dark L&F that is known to work with IDEA (or at least worth trying)?

Thanks