WebSphere Process Server, the flagship product in the WebSphere Business Process Management suite, is built on top of WebSphere Application Server v6.0.
Here's a picture to show the relationship. I drew it myself, so it's really bare bones because I don't draw well, and so that no one will mistake it for an official item from WebSphere marketing.
The WebSphere Process Server v6.0 Stack
Now the latest version of WPS, v6.0.1, is built on top of WebSphere Enterprise Service Bus v6.0.1, which is built on top of WAS v6.0. So it looks like this:
The WebSphere Process Server v6.0.1 Stack
Thus you can deploy J2EE/WAS apps to WPS or WESB just as if you're deploying them to WAS because, in fact, you really are. For that matter, you can deploy WESB apps to WPS. The products are built on top of each other, so the more basic products are really inside the more sophisticated ones.