Can you use a M-AUDIO FAST TRACK to record keyboard, through a guitar jack?

I just bought the Avid M-Audio Fast Track USB interface to do home recording, and I'm trying to decide if it's worth keeping or trading it in for one that suits my needs better. I plan on only recording vocals, acoustic guitar and keyboard. Now, the only interface in stock only had 3 slots - one for a microphone, one for a guitar, and one for headphones. Since my keyboard has a 1/4 inch output jack the exact same as my guitar, can I use this device and jack to record with my keyboard, or do I need a completely different device?