It's right across the street from the west side, I believe. I'm sure you could technically walk it(although I'm not sure if they allow this or not?), but if I remeber correctly there's a rather long (well...it would be a long walk anyway) drive from where you turn in to TL to the entrance of the park.
I'd suggest, if you're already at downtown disney, why not just take the bus over there? I believe the DD bus loops include TL. (although...I'm not sure if the TL stop is before or after DD...definitly something to check out)