I wrote a simple utility to help manually working on styles from a StyleBook in XE4, the version for XE5 is now available on CodeCentral. The original blog post with the description of the problem and of the solution is at http://blog.marcocantu.com/blog/couple_tips_xe4_fmx_styles.html.

The new CodeCentral submission is at cc.embarcadero.com/item/29623