- Use Xposed Installer to launch Unicon.
- When Unicon tells you it needs to move itself, just click Move to get rid of the dialog.
- Select your icon pack, and click Apply.
- Unicon will ask you to either let it restart the launcher, or to let it soft reboot your phone. Regardless of which dialog comes up, click Later to get rid of it.
- Press your Back button to get back to Xposed Installer.
- Go to the Framework page of Xposed Installer, and select Soft Reboot there, then click Yes.
After this is done, you should have your icon theme active. Unfortunately, there are some caveats. Firstly, your icon theme will be lost on a device reboot, and you'll need to do all this again every time, until Unicon gets fixed. Secondly, some icon themes appear to not work with this method, so YMMV.
Note: You DO NOT NEED SuperSU. The superuser in CM11 works with this procedure, and SuperSU does not seem to do anything at all to make any of this easier. In fact, I don't even have SuperSU installed anymore.