Alex,
Christ is Risen!
The Troica is kept in a holder in the vestabule of the church. The ushers are at the back of the nave during the liturgy.
At the appropriate time, the usher simply lights the troica, walks it up just behind the tetrapod and holds it there, slightly elevated, for the duration of the required portion of the Liturgy.
Then, he walks back, extinguished it, and places it in the holder until the next time it is needed.
With all the mystery surronding the rest of our tradition, this one is seemingly very logical.
Regards,
Deacon El
