You can't open the door from either side without a key.
Getting a key is easy, though. Butcher kobolds in the Warrens. At level 50, you can pull hordes of them and just murder them all. Shouldn't take but a few hours.
Also, you said you are a dwarf, and then reference an SK. That would be a sweet combo!
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If you want to "cheat", you can bring a necro with you and have him let you in to the city. Go to the merchant and duel the necro. Once he casts ignite bones on you, you are well liked in Paineel for like 18 seconds. Then you can buy the key.