Can you give a specific example? It isn't clear whether you are trying to compose a regular expression from the token attributes, or whether you are using them to specify min/max value ranges.
All of the advanced question attributes are parsed by EM, except for the regular expression validation in the core validation option. So if you want to specify min/max answers, or min/max numerical value, you can use those options.
If you really need to do dynamic regular expression validation, then you could use new the em_validation_q advanced question option. Say your regular expression pattern is composed of two attributes, you could set the em_validation_q equation to:
regexMatch(implode('',TOKEN:ATTRIBUTE_2,TOKEN:ATTRIBUTE_1),this)
where
this will end up referring to the current variable name.