The first thing you need is the manual- the k7vta mostly uses jumpers. find the fsb jumper, set it to 133. This will give you 1400 processor speed. You also won't have much success changing the multiplier unless the processor has been unlocked.
I have a k7vta in one of our machines, and I'd be of more help if we weren't in the middle of major renovations- can't find the manual, hell, I can't find anything....
Edit- the pro board may be different, my error, but getting the fsb to 133 is the key to 1400 no matter how you get there....