Yeah, there's something out there about changing your config files to accomodate this (I can't remember where), but, I have to ask this: why would you want to?
If you're using TC and notice a new convoy target anywhere near an intercept range, you'll have plenty of time to slow it down and plot your course. You're talking pretty good ranges here. Heck, just hit backspace or change stations and you're back at regular time.
I know for myself that I'd be going nuts if my TC went back to 1 everytime a new map contact came up, because it happens constantly, especially in stock.
My .02
