you can't currently paste one, no.

The fastest way at present is to add  a "nest"  (eg {{+image}}), then save, and click on the nest.

If the name is "+image", it will default to an Image type.  If you use another name you can save and then change the type, or you can specify the type in the nest, eg {{+my new image|type:image}}

soon we'll be adding special interface to make this much easier!