There is nothing different between how JBoss or Tomcat sees your jar's in web-inf/lib. They are automatically picked up if using JEE 5/6, if using earlier then you have to refer to them from manifest.mf.
If you are missing JBoss in "Run As.." but have a Tomcat there then i'll assume is because you only added a Tomcat server and have not yet added a JBoss Server ( you do that via File > New> Server and then choose JBoss Enterprise or Community server depending on what you have available to you).
And if that would have been available then it would still not be the right place to add spring or other jars for your WAR.