"Need" a transit visa might be an overstatement. No, there is no dedicated path to the departure lounge for those in transit without a visa. You will be herded to immigration control. Depending upon the agent, you may be escorted back upstairs to departures, or you might have to wait for an airline rep (Swissport?) to come fetch you, or you might be admitted with the understanding that you're headed straight to pre-departure security. What is unlikely (but possible!) is that you'll be returned to Paris. None of this would be considered "standard procedure" so expect delays.
When I asked the embassy if I could obtain a visa, the answer was "No." After all, no visa is needed by the government if you are same-day transiting the airport. How can you need a visa you can't even request?
I hope you share your experience with us. And if someone else stumbles on this thread before travel, consider contacting the Swissport office @ ALG and see if they can provide guidance. I was under the impression that the agents for multiple airlines manage transit situations when they are aware of them...but I don't know.
P.S. Apparently they don't like electronic boarding passes @ immigration, so have paper and better yet have an airline-printed BP. Despite IB saying that
e-BP are accepted. Maybe at security?