Lambics are notoriously difficult to brew. A "true" lambic can only be made in Belgium, where the fermenting vessel is left open, and naturally occurring yeast causes the wort to spontaneously ferment. I'm not aware of any strains of "true" lambic bacteria commercially available. A second problem is that the hops are usually aged a year prior to the boil, and the wort is then allowed to "sour" over a period of 12-24 months prior to bottling.
When American microbreweries try to replicate lambics, they usually do so by using a collection of yeasts, and employing specialized fermentation techniques. A quick internet search suggests that Wisconsin uses both a "souring fermentation," and "two types of Brettanomyces, an ale yeast and a couple of different bacteria."
I don't like telling people not to try exciting new stuff so. . . If you can find a yeast and a fermentation process that is (1) close to the taste of a commercial "lambic," and (2) feasible for home production, PM me and tell me how! We'll incorporate, and start our OWN darn brewery!
You should probably start a similar fruit beer for a standard fermentation, though, as a fall-back. Maybe a cherry wheat using a Belgian yeast? You can add a little bit of lactose for sweetness, and use Sorachi Ace Hops to replicate a bit of the "sour" flavor of a lambic.