When trying this plugin with eclipse 3.3 I got the "The activator com.sofor.lsseditor.LssEditorPlugin for bundle com.sofor.lsseditor is invalid" error already mentioned by someone on the forum.
So I decided to quickly repackage it as 3.3 plugin project and recompile.
The result is attached. You can install it by simply copy the com.sofor.lsseditor_0.6.1.jar to your eclipse "plugins/" directory (you do *not* need to unpack the jar).
The jar also contains all sources. I you want to start hacking on it, simply make sure you have the "Eclipse Plug-In Development Environment" (PDE) installed, and choose "File | Import... | General/Existing Projects into Workspace" and choose "com.sofor.lsseditor_0.6.1.jar" as "Select archive file".
To re-package use "Export... | Deployable plug-ins and fragments" from the projects context menu.
The content is the same as of version 0.6.0. I only replaced the import of the deprecated "org.eclipse.jface.text.Assert" with the current "org.eclipse.core.runtime.Assert", and commented 2 lines regarding the unused "proposals" member in LssAutoEditStrategy.java to get rid of compiler warnings.
Yes, I am well aware that this project seems quite dead, but maybe someone wants to kill some time on this one while waiting for the real "Domino Designer on Eclipse" to arrive ;-)
LSS Editor Plugin 0.6.1