Using the Ink Manager plug-in, it is possible to assign a DGC Curve for an ink under the "Ink Options" window. But when the drop-down list is opened, only a few (Default) DGC curves are shown and not the entire list (including Custom Curves).
Is it possible to assign custom DGC curves?
Ink Manager shows only a list of hard coded curves in the drop-down list and not the entire list with custom curves. You can type any name manually and it is only the string that is saved to the XMP of the file, and nothing is applied in Adobe® Illustrator®. The information stored in XMP is applied when the file is output or ripped.