I second the request for any 3E information on Lankhmar---loved the books, & actually ran the setting for a little while. Would love to run it again, as well as use some of the elements from the setting (Nehwonian Ghouls!).
As for the Lankhmar boxed set---I used to have it, & promptly got rid of it. The other Lankhmar materials were much better. Basically, think of the boxed set as a really simplified version of 2nd Ed. They had the warrior (fighter) class, the rogue (thief) class, the white wizard class (basically an arcane spellcaster with the priest spell list) & the black wizard (mages). Sort of like an introductory set for the Lankhmar stuff. IMHO, not worth the money---getting a copy of the sourcebook allows more options, such as the racial bonuses for which culture of human you choose, as well as the "template" rules for being a priest of a Nehwonian deity (more or less which classes & ALs could be a "priest," along with any perks they'd get for being 1), playing other classes modified for the setting (such as paladins, rangers, & bards), & notes on being an elemental mage (air, earth, fire, ice, water).
On a side note, I always liked using the Skills & Powers rules for 2nd Ed. Lankhmar, because IMHO it allowed for more rewarding options for the PCs, especially for rangers & bards who weren't allowed spellcasting abilities in Nehwon.
I recall LONG ago, back on Eric Noah's boards, that there was a brief mention of making an unofficial 3E conversion of Lankhmar. Anyone else recall this, or maybe know what happened to it?