In IDEDOS 0.90 it was already possible to enter image files (D64, D71, D81, T64) in the file manager like directories and start programs from them using the vd64 plugins.
Now in recent IDEDOS 0.91 betas this was extended to support DOS commands and copy operations, so that it's possible to read/write, rename, or delete files also in image files.
The vd64 0.05 plugins were updated now to support copy out. This can be tested with the IDEDOS 0.91 20100809 beta and vd64 0.05 from:
http://singularcrew.hu/ide64warez/site/Tools/Plugins/vd64-plugin-0.05.zip
http://singularcrew.hu/idedos/beta/
Later all other operations like copy in, rename, etc. are planned to be supported in the next versions.
If you have plans to support other image files as well, the API is documented in the updated IDE64 user's guide at "9.1.2 Virtual filesystem interface" around page 78:
http://singularcrew.hu/idedos/beta/IDE64_users_guide_beta.pdf
In theory the copy in interface should work as well however it was used yet.
Directory handling is not supported yet by the API, as probably there will be some tricks to support the recursive copy/delete operations. Anyway there's still a lot to explore without directories too ;)