Is it even that much of a difference? What with PF being basically more of the same with some "improvements" and even more classes to cater to the fanbase that was put off by 4e's approach.
To qualify to become a shadowdancer, a character must fulfill all the following criteria.
Feats: Combat Reflexes, Dodge, Mobility.
Skills: Stealth 5 ranks*, Perform (dance) 2 ranks.
3 feats and feats are available at 1st, 3rd, 5th character level. Ranks are available at 1/level and a +3 bonus for being a class skill instead of 4 ranks at level 1 or 2 for cross class. So RAW one can meet the requirements by 5th in any class.
But these are guidelines more than hard rules and I use them for myself more than against the DM so that I don't run amok doing anything I like and just yelling 'pirate' like a landbound jack sparrow. He has strengths and weaknesses, skills he has and skills he lacks. Claiming to have open/close and lesser darkness 3/day prevents me the player from spamming or getting too 'creative' if stuck in a spot.