UTF8 Regex in 1.2.x

So, I've been pounding the web for info on UTF8 in Ruby and Rails the past couple days to concoct some validations that allow UTF8 characters. I have discovered that with the patches applied in Rails 1.2, I can get a little further by doing the following declaring $KCODE = 'UTF8' in environment.rb and by adding /u to regex expressions.

The only thing not working now is the ability to define a range of \x characters in a regex.

So, this /^[a-zA-Z\xE4]*?&/u will validate that a string is allowed to have an รค in it. Perfect.

But... this fails /^[a-zA-Z\xE4-\xE6]*?&/u

But... this works /^[a-zA-Z\xE4\xE5\xE6]*?&/u

I've boiled the experiments down to realizing I can't define a range with \x

Is this just one of those things that just doesn't work yet WRT Ruby/Rails/UTF8, or is there another syntax? I've scoured all the regex docs I can find.