The reason i ask is that in the B5 mod i have changed quite a few of the promotions so instead of unit upgrades they are treated as Crew Training. The only problem i have is that there are one or two Promotions that don't equate to the Crew Training idea and would still fall into the Unit Upgrades sphere.
Having gone through the xml file for Promotions it might require that there be a new xml file and a renaming of the original so instead of having Civ4PromotionInfos you have Civ4CrewPromotions and Civ4Unit Promotions. All you would need to do then is divide up the current promotions into the relevant folder.
There are also a few other changes that would need to be made. The promotion buttons would need to be different colours for Unit and Crew promotions and there would need to be a different set of parameters added. Unit upgrades would only be able to be done at a City(Solar system for B5) or a Fort/Military base (Starbase for B5) and there would be a cost involved. Crew Promotions would also cost, at least for the crew to become Trained. Once a unit has a Trained Crew Promotion it can improve that from Trained to Experienced to Veteran to Elite at no cost. Alternatively if the Unit has a Trained Officers Promotion then the Unit can earn Crew Promotions without having to pay for it.
I could have posted this on the main request page but wanted to know how far along with your own version of this you are. I can always repost this request there.