Go to Edit>Keyboard Customization...
If it exists, that's where you'll find it.
Unfortunately, Premiere's "step" is locked to 1 frame for a "small step" and 5 frames for a "big step." I'd prefer 10 frames, myself, or even better, a user customizable setting.
You can jump in specific increments, however, by using the numeric keypad on your keyboard. Use the "+" or "-" keys to specify a forward or backward jump, and then use the digits (and optionally, the "." key) to specify the jump. So, for 1 second forward, you'd type:
That says, "move forward 1 second and 0 frames. You could also type:
That's like saying "move forward 1:00 seconds." Same result as the above.
Note that you need to deselect all clips before doing this, otherwise the move command applies to the clip itself and not the CTI. I've actually made a feature request to alter this behavior; drives me craaaaazy.
Ooo, I hope they don't change it. Clip selection seems by far the best modifier for that function. Much like the Home/End keys.