i think we have a small misunderstanding here. What I meant to recommend was to do the following, given the scenario that the DW customer has neither AIX nor WF available.
1. Add a new index field (int) to your file cabinet like you usually would and call it "ID" or something like that.
2. Connect to your database and create a script/trigger which copies data from the field "DocID" to the field "ID" in the same row.
From a technical standpoint, you are not messing much with the database and the only thing which might happen is that if you have the "Index Data Backup in storage location" enabled, the data from the field "ID" might not show up in these files - which does not really matter, because the DocID already shows up there.
On the other hand, yes, you are right, there are better ways to do that - namely AIX or WF.
Yes, when you update your DW System, the upgrade might break your script/trigger, you need to check this after each update.
Regarding DW support (as far as I know): DocuWare will still provide support to your system if you do not mess up the database too much - they just won't support the parts you messed with or require you to remove your customizations before working on the database (at least that's what they say, they have not done this to me yet).
However, I can only talk about the EMEA Support team and my personal expiriences.
Regarding US Support, we might want to wait for an answer by Phil.
Greetings from Germany,
Simon H. Hellmann
DocuWare System Consultant