That depends....are you looking to get to a specific park, or to a hotel?
If you use MapQuest.com, you can enter your starting address, and in the your destination box, there's a drop down box where you can select Amusement and Theme Parks. Click that, and use Orlando as the city and 32830-2203 as the zip code.
It will then give you a whole slew of amusement parks in Orlando. Click on the W, and there's a couple Disney locations. They're not perfect. The only ones that I can find are Animal Kingdom, and Fantasia Gardens. The others are executive offices, seemingly off-property.
Or, if you're looking to get to a hotel, instead of Amusement and Theme Parks, select Hotels. The Disney resorts are under D on the 2nd and 3rd pages.
If none of those have exactly what you're looking for, the directions will still get you on property, and from there, you can use the signs to wherever it is you're going.