You may remember
this post, and the order of precedence for the ministers of the
consistorium; I'll repeat it here - it's taken from the Theodosian Code (C.Th XI. 18 - Feb 15th AD412):
Vir Illustres
1. Praetorian Prefect
2. Magistri Militum (The masters of the soldiers)
3. Comes Domesticorum (the commander of the household troops)
4. Praepositus sacri cubiculi (Controller of the Sacred Bedchamber)
5. Primicerius sacri cubiculi (Superintendent of the Sacred Bedchamber)
6. Castrensis Sacri Palati (Steward of the sacred palace)
7. Comes sacrae vestis (Companion of the Sacred Vestments)
8. Magister Officiorum (master of offices)
9. Quaestor
10. Comes Sacri Privati / Largitionem (the controllers of the sacred imperial and private treasury)
Vir Spectabiles
11. Primicerius Notariorum (the chief of the imperial secretaries)
12. Comites Consistiorum (the companions of the imperial consistory)
13. Magistrii Scrinii (the masters of the bureaus)
14. Comes archiatrorum (the controller of the chief physicians)
15. Comes Stabuli (controller of the stable)
16. Cura Palatii (the curator of the palace)
17. Comes Dispositionum (the controller of arrangements)
18. Magister admissionum (the master of admissions)
Unfortunately we don't know much about the internal workings of the consistorium, beyond the titles of those present. The Praetorian Prefect was the highest in rank, but he may not have been the 'master of ceremonies' as such - the title
comes dispositionum might suggest that this minister had some organisational function within the consistorium, while the
magister admissionum might have announced new arrivals or controlled access generally. The
quaestor was originally the emperor's chief legal advisor and proclaimed his edicts to the senate when necessary, so he might have had a wider role as a spokesman.
Consistorium meetings would involve all of the above when they were present at court, besides various
silentiarii acting as ushers, court guards (
candidati, protectores), and secretaries (
notarii). Plus the emperor himself, of course, when he was available.