You could nest the series of numerals in a Span tag, and apply Alt Text. For example the sentence "Section 508 Standards apply to electronic and information technology procured by the federal government." would be tagged like this, with the Alt Text "five zero eight" applied to the Span tag:
Standards apply to ...
Thanks that does appear to work. If anyone has other ideas I'm open to those too though. I have a 700+ page document I'm working on with thousands of numbers that I would have to set up as spans.
The right way to handle this is to leave the numbers alone. The assistive technologies take care of numbers and abbreviations in their own way and end users are familiar with those ways. You may be expecting to hear "section five oh eight" but the assistive technology user will understand and if it really bothers them they have the ability to tweak the pronunciation within the assistive technology.
Adding a span and alt text for numbers is a waste of your time, doesn't avoid any compliance concerns (since there are none), and changes the experience that the end user expects from their tool. Don't do it!