Sorry for late reply.
If I understood your question correctly, then yes.
But I have dug around a bit and found out that maybe the easiest way to have transformation from ims -> epub is following:
1. Carry out html and picture files from IMS
2. Build html index/table of contents based on the imsmanifest.xml
3. Convert these html files to epub (as calibre successfully creates epub book from single index/table of contents file)
So it would be awesome if this whole procedure could be done in calibre as usual conversion.