If you are talking about the Qt styles ( QStyle ) that are used in traditional KDE KDE themes (themes without a plasma or ini) then yes, you can do this to some extent, although you may have to tweak / fix some (or more) things as they are mainly written for the purpose of the KDE theme. One good example would be fixing or ensuring compatibility between platforms (the theme could use additional libraries for a specific platform). Then there is also a licensing issue, which you should definitely take into account, since most of these topics are under the GNU GPL.
Qt Stylesheets, , KDE - Qt , KDE .