This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Basically, to use accesskey the element generally needs to be something you can tab to, like a link or a form element. It's also good practice to give an indication of the access key using the title attribute. Note that how the access key is accessed is browser (or OS?) specific. For example, I believe access is via Alt-N on IE/Windows and via Ctrl-N on the Mac.
I don't know how this translates to Struts though.