You can still use JSF 1.2 with Facelets, even in old JBoss releases.
JBoss 4.2 and JBoss 5.0 will support JSF 1.2, JSP 2.1 and Servlet 1.5 out of the box. In fact, the JBoss 5.0 beta is already out. So you can try this.
ref to Stan's message; i think, it's a small typo there: it's servlet 2.5 not 1.5 :)