work permit passport stamp/garda id?

offtheboat

I have a question that should be fairly easy if any americans have gone through this. I'm an american currently staying in the UK (belfast) on my 6 month passport. I have an irish company that i've gone through all the steps of the work permit process with, have applied, and now I'm weeks away from the DETE review of it. So, trusting that I'm approved, I know that next i need a special stamp in my passport and a garda ID. The sticky and various other websites explain well enough the garda id part. What i don't know is what is the least costly way for me to get the passport stamp?

Obviously i could fly back to the US and into ireland to get it, but that would be crazy expensive & wasteful to buy tickets at the last minute to do. So being that I'm in belfast, I'm wondering if i can do one of the following:
1. bus to dublin and get a stamp at some authority there?
2. fly to dublin and get the stamp at passport control (if i go through it flying from uk to ireland, cant remember if i do).
3. Fly out of the EU (switzerland) and back into ireland.

Has anyone been through this that can share how they did it or know of? If you don't know, please don't just be an internet-expert and assume things and answer because that could end pretty poorly for me if you assumed wrongly.

Thanks much!
alan

offtheboat

& the job is in dublin, just in case that is confusing with me talking about currently being in belfast. Just to be clear, the job isnt in Northern ireland...