(I think the previous poster assumed you were using iWS. I'll assume that you are using iAS 6.x.)
I'm not sure what you mean by "hot deploy". Usually people associate "hot deploy" with the ability to drop in class files into a running server. (Which will then detect the change in timestamp and reload the class without a restart.) iAS has this feature but it is disabled by default. (Because it isn't a good idea for production servers, and there are some complications related to helper classes and sessions.)
But it sounds like you are really looking for a feature commonly called a "drop in directory". Where you just drop a WAR/EAR file into a directory and the appserver automatically deploys it upon start-up. (Tomcat only does this at check of the webapps directory at startup.)
There is no "drop in directory" for iAS 6.x. It would be pretty easy to create a script to do this for you, if there is some reason you want it though. Just create a script to execute iasdeploy against an arbitrary diretory and then create a new start script that calls the deploy script and then calls iascontrol start.
Personally, I find it just as easy to execute an
Ant script has to copy a file over to a directory. That way I don't have to worry about packaging or file permissions.
David