Resort-to-resort transportation is technically done through Downtown Disney, not the TTC. However, it's usually faster to take resort transportation to the nearest park and then take that park's transportation to the resort you want to go to, assuming that park is open when you want to go and when you want to return to your resort. In your case, it might be faster to take the bus from Wilderness Lodge to MGM then take the boat to the Boardwalk or walk (I find it faster to walk.) You could also take the WL boat to MK and take the bus to the BW from there...there are several options.