It can be done, but the you have to recreate the part from scratch using automation and when you get to the part where you are adding cells, then you would make your modifications.
The reason for this is because the cellreferences object on the part is read only using automation.
wow, that's a disappointment - re-creating the part with pin mapping etc just to swap out a cell. I thought this would have been a pretty obvious requirement for a Library Manager tool. Do you know if we are still in the mode where I can request a license to decrypt the files so I can process ASCII?
Yes, if you can get the license to decrypt and encrypt files, then you can still modify the ASCII files.