I think there is actually an alliance war group finder in the same menu as the pve one. Never used it and i doubt others do either so "lfg" in chat is probably your best bet.
The absolutely easiest way is just type "Lfg" in the zone chat in Cyrodiil. If there are many in your faction online at the time you will most likely get an invite quite fast. But how fast it goes depends on how many are online. Sometimes it can take longer, and other times you just have to make your own group.
Edited by VDoom1 on January 1, 2017 5:51PM
We Fight For Cyrodiil.
We fight for The Daggerfall Covenant.
We fight for The Aldmeri Dominion.
We fight for The Ebonheart Pact.
We fight for Tamriel!
I think the group leaders nowadays use the zone when they look for new group members. They have their set of rules. Some demand the use of voice chat and therefore not necessary pick up lfg.
A is for Atronach.
B is for Bungler's Bane.
C is for Comberry.