Yes, it can. At least i did this for Plumtree ver.5.*
But it may required some changes in your code as well. I don't know how much you know about plumtree, try look here www.plumtree.com -> Developer -> Develper resources. You will need to register there. Then see forums.
The main chalange is that sometimes you will need RENDER plumtree page (where your portlet is), as soon as your server side code is done. So in real I have my own version of ActionRouter because to be back you can not just write URL in your action.properties file.
here id my route method
To be more correct, i used to Struts and at the some time my own verion some router classes. You can find more information at plumtree developer resource.