There is a very good chance that any answer you get here will be of no use to you because Elastix won’t let you implement it, which is why you probably should be using an Elatix forum.
You can’t actually log in to queues, so I’ll have to make a guess at what you really wanted.
Asterisk offers an AgentLogin mode, where agents are only able to take incoming calls, and which is the simplest way to have a hot desking agent.
It used to have an AgentCallbackLogin application, that would ring the agent for incoming calls, but this was deprecated, and may have been removed, because it had some limitations and a facility with similar limitation could be simulated using local channels. Sample dialplan and scripting was supplied to implement this, and was included in the Asterisk source tree. I think this is now outside of the source tree, but I don’t want to spend time tracing it.
You can, of course, associate any extension number with any device (although GUIs often confuse the issue by giving devices names that look like the extension number used to access them), so there might be a soluton where you created and deleted extensions for use by the agents, to take incoming calls.