Another thing you could try is directly including the character:
[[:alpha:]'#Chr(8217)#]{2,10}
However I'm not sure if that will work with a CF regex. If not, you still have the option to use Java regex within CF. This is easy to do, and enables you to use a far wider range of regex functionality, almost certainly including unicode support.
If you're doing replacements, you can do a Java Regex directly on a CF string, for example:
<cfset NewString = OrigString.replaceAll( 'ajavaregex' , 'replacement' )/>
For other functionality (e.g. getting an array of matches, callback functions on replace), I have created Java RegEx Utilities - a single component that simplifies these functionality into a single function call.