Hello Paolo,
I just saw the version in title.
JCE editor is blocked from sellacious because few JCE plugins conflict with sellacious backend CSS and give sellers unnecessary permissions.
We have created an editor CKEditor4 with the help of the CKEditor plugin, which is sellacious compatible and already installed in 1.7.3. You can view more features of this editor from Joomla Administrator > Extensions > Plugins.
I suggest you use this editor except for JCE.
Thank You