Replacing XML nodes

I’m now working on a flash project that will load a standard HTML site with all the advantages of flash. My problem is that I use the WC3 recommended <strong> tags, versus the depreciated <b> tags that flash wants. I already have the page loaded as an XML instance, but I need to know how I can replace all of the WC3 tags (em and strong) with their flash-friendly versions (i and b). Thanks!