If you are looking for a JSR 286 (Portlet 2) or JSR 168 (Portlet 1) compliant portlet, what you have read is correct. You need a portlet container. JBoss used to have JBoss Portal that should fit in your stack if you are focused on the JBoss products. In fact, you can find an entire bridge between JBoss Portal and the stack you are using. If you decide that you need a portal and want to look to other apps, I have successfully run Liferay on JBoss in the past.
At the same time, you can get something that looks and behaves like a portlet by using iframes or a div and JavaScript and back-end coding. With more specifics on what you want your pseudo-portlets to do, the community can more specifically help you figure out if wiring your own smaller framework within your existing code or attempting to have some sort of larger portlet container seems more reasonable. If you want to reproduce all of the Portlet 1 or 2 spec, I'd go with the container. If you want to reproduce a mini-iGoogle, you can probably do someting with JS and HTML.
EDIT: Looking through other questions with the same portlet tag, I found the jQuery UI Sortable - Portlets demo that might provide just the portlet-like features you are looking for without an entire Portal framework. It does, of course, pull in jQuery UI.