:: returning after reading first post more slowly ::
There are patterns that I might be able to do lets say 25,000 lines at a time but it involves seeing the pattern, matching and then converting to lower case. is that possible. I'll show you 2 lines maybe you can see the pattern and help.
Unfortunately you didn't show two lines. You only ended up showing one line, and you can't deduce a pattern from that.
:: vague mental association with some process in mathematics or possibly historical linguistics where you do in fact make a rule based on only one instance ::
mod_rewrite alone can't change the case of an URL. It can detect requests in a case-insensitive way, like picking up .jpg, .Jpg and .JPG in a single rule. But there's no straightforward* way to make them all output .jpg other than by individual redirects. The same applies to any mass replacement like lowline-to-hyphen (or, ahem, vice versa**).
That's why g1 originally said "php script". (If you read the apache subforum regularly, you will see that g1 very often says "php script". Probably because people only come here when they've got questions that would defeat the ordinary htaccess. Nothing to do with the fact that any solution involving php bumps the follow-up questions into a different subforum ;)) Among other things, php can change cases standing on its head. Heck, even javascript can do it. But mod_rewrite can't.
* There's a post by jdmorgan illustrating the non-straightforward way. It relies on flags like [C] and [N] that normal people approach with EXTREME CAUTION.
** Yes, I know, it's just me. But I always think hyphens look spammy. get-your-cheap-widgets-here dot biz, kind of thing.