Do you mean through the browser? Nope, must be done via the Creo Parametric application via a workspace. There is an import to workspace feature documented below:
https://support.ptc.com/help/wnc/r12.0.2.0/en/#page/Windchill_Help_Center%2FProEWCIntegGWObjImportOview.html%23
It can handle a large number of items. Remember once checked in, you should managed in Windchill from there. I would not use this as a release to system and keep working offline. During our initial migration, I did most of the migration efforts, creeping up behind the engineers. Once we had everything, we flipped the switch and moved them all in.
