Well,
short answer YES !!
longer explaining :
it's like you fancy all the new maillots and like your team to wear them. Need to first get them into the 3D/Cyclsit/Cloth folder under a correctly named folder, that is the same name as in the field of the Sponsor table in the DB. Or if you get a new race, you have to add it to the STA_race and so on.
The key is that XML has been provided by Cyanide in a very easy standard form. Only the biggest races have individual xml-files, and even them are in some cases not correct.
So TWO things needed.
The new XML and copy it to XML/Classification folder,
then edit the name into the DB for that race (STA_race table).
Any editor will do nicely (I think) as far as you can edit separate Tables and field within them. I'm using Lachi editor most of the time.
So this stuff has NOTHING to do with the Stage Editor or Stagemaker. (Beside selecting KOM categories)
TWO different things that together makes the race.
Only thing that is good if the stagemaker cooperate with the xml creator or at least stick to the setup of the race in real life. Some stagemakers have asked me if I could do a setup and told me what categories they are using in their races. Good combo makes great results. Mostly I have adjusted XMLs based on what stagemakers have come up with, but some cases are hopeless to say the least. That's more Cyanide limited XML setup and how they have programmed the core program to read phraces in the XML. Poorly IMHO.
One issue is the intermediate sprints in the Giro. Can't be handle since they are THREE types of point system based on flat, hilly or mountain stage. KoM can handle this, but not sprints. I've tried to crack it but I haven't got the game programming at hand (of course) so I don't really know whatever stuff is stored when riders approach a sprint. It would have been a simple IF_THEN like the KoMs. Perhaps I crack it, perhaps it's not possible.
As I found out in the beginning lots of folks doesn't care whatever happen on sprints and KoMs, but then I thought many races have tended to have these things more and more important. More focus on TV and all that and certain minor 3-4 day races with flat stages makes hell of a different if they got correct or wrongly XML setups. The idea on Eneco was that bonus seconds on those Golden Km was to enhance the race that normally have very little time gaps on the first 3 stages. Primus beer wanted to stick with their combativity jersey (black one), so in this game it would be a good substitute for KoMs.
In some cases Cyanide left the very old bonus system (in Cont_??.xml) -20,-10,-6 seconds that would kill a tight race IMHO. NO race today use these bonuses on the finish line. It doesn't affect the game but makes it less real IMHO.
Now you got the long version of explaining and I hope you understood. Would have been killing me trying this in French, so hopefully you can get it translated.