No. Only the same generation software can be synced together. For instance, CC3 can transfer character to iClone 7, or CC4 can transfer character to iClone 8.
Take note that iClone 8 and CC4 are backwards compatible, meaning that iClone 8 can read iClone 7 projects.
Also, the Content Manager in iClone 8 and CC4 can read contents which were created using iClone 7and CC3.
Content Sharing with iClone 8 and Character Creator 4: