Can かっこいい be used to describe men and women? I have usually seen the term used to reference men.
First, allow me to apologize for the length of this answer.
かわいい and かっこいい are not mutually exclusive and they have no absolute link to either sex or gender, but they do often tend to engender some stereotypical gender traits. While かっこいい is usually reserved for masculine traits and かわいい to feminine ones, there is substantial overlap.
A person could be considered かわいい based on their face and/or demeanor, but かっこいい based on their fashion sense. The opposite is also true.
One celebrity could be considered かわいい by one observer and かっこいい by another based on the same exact criteria. Person A might consider an outfit to be cute and Person B might consider it to be cool (or neither…or both). The choice of word which one uses to describe an image will be informed by and can inform others of their own particular subjective preferences.
Following are some generalizations (made by myself) on what might be considered more likely to be held as one trait or the other. Keep in mind that these are by no means comprehensive, exclusive to everyone, or without the ability to be redefined at some point:
かっこいい: Cool, tough, rebellious, masculine, angular, hard, modern (trendy), aloof, handsome, bold...
可愛い: Simple, soft, comforting, pleasant, soft, round, traditional, friendly, cute, considerate...
Finally, while likely off-topic and not in great common usage, the merging of かっこいい and かわいい to form かっこかわいい can still be found in at least one dictionary.
Yesterday I saw a TV program in which one guest (a female singer) described another female singer as かっこいい, so this is a proof that people do use it to describe women. How common? I'll have to leave this to others.