I lived through this era and can confirm that Z100 was VERY alternative sounding from 93-96. Technically, the majority of the titles they played did eventually chart in the higher reaches of the CHR chart but they also played some songs that were alternative only (Nine Inch Nails, White Zombie, Pearl Jam deep cuts, etc). They were one of the stations that aired Pearl Jam's show from Atlanta live in April of 94. In reality, they essentially mirrored MTV at the time minus the hardcore rap or metal and the station sounded pretty great. As my tastes leaned more alternative, I ended up jumping ship and went to K-Rock in 96 (Q104.3 was also great at the time but that station did terribly ratings-wise).
Fun fact but the first Jingle Ball they did in 94 was almost all alternative acts with Green Day, Hole, Weezer, Sheryl Crow, Toad The Wet Sprocket, Pansy Division with a side order of, um, Bon Jovi.