I would read the Avalon documentation on this page first: http://www.altera.com/literature/quartus2/lit-qts-sopc.jsp (http://www.altera.com/literature/quartus2/lit-qts-sopc.jsp)
There is also this document that talks about hooking up an external master (DSP device):
http://www.altera.com/literature/an/an397.pdf (
http://www.altera.com/literature/an/an397.pdf)
What you are looking for are details on creating Avalon masters. As long as your master follows the Avalon switch fabric specification you should be all set. Sorry I can't be of more help but there is no single answer for the question you have asked.