I'm using jboss/tomcat 3.2.2 and the startup is quite lengthly to restart the whole app server.
I wanted to know if in the jmx-console (or elsewhere) there is a way to restart just tomcat?
Not in jmx-console AFAIK. However, you could try redeploying the Tomcat SAR - "touch" the jboss-service.xml. It should also cause redeployment of all dependent services e.g. WARs