I cannot verify that in my environment but if it is a Dynamic Web Project first I would try to add org.jboss.tools.jsf.jsfnature in list of natures in .project file.
If you have your project under source control management you can try to use add JSF capabilities without copying JSF libraries, then just review changes and decide if they work for you.
Sorry for the late answer.
I added the JSF capabilities by modifying the .project file, and when I do right click / JBoss Tools on the project, I see that the JSF capabilities are enabled.
The xhtml pages are opened with the "JBoss Tool HTML editor".
But I still don't have any code completion inside the xhtml pages...
The version of your eclipse 3.4.1 is pretty old, could you try update to newest, eclipse 3.5.2 and try JBoss Tools for this version?
Sadly I can't choose my IDE.
I'm bound to use IBM RAD 7.5 (188.8.131.52), which is the last version and is based on eclipse 3.4.1. Otherwise I'll use the last version of eclipse and probably have no problem...