As nikesh.yadav already pointed, there are only two true conventional browsers that will handle focus as expected for elements other anchors and forms for certain. That is, IE and FX.
You can write a loop function that iterates through table elements that should receive focus and use a declaration like: tag[i].tabIndex = "auto"; to make them receive focus. This additionally prevents you from breaking the tab order on your document.
It will enable your client to tab through your table rows, cells and/or other desired elements the conventional way, (or browser specific), without having to explain that there are keys with added functionality and how to use them.