This is a very easy drive.
From the Poly retrace your drive into the resort. On the main resort drive, you go past the MK Parking Gate, keep going south. As you go past the Swan and Dolphin on your left, you need to go left/east on the next major road. I cannot remember if there is a cloverleaf exchange or not, but you need to head east.
You will go past the Tower of Terror on the right, the Boardwalk on the left, past the Carribean Beach Resort on the right. You'll come to an overpass interchange, exit to the right before the overpass. You're now headed southeast. You'll go under the arch greeting guests to WDW. The next interchange, coming up very fast is Interstate 4. Go over I-4 then immediately exit to the right. After you wind around, you are neaded northeast on I-4.
Stay on I-4 all the way to Universal. You go past Sea World on the right. The exits to US/IA are very well marked. It's a very short drive, I'd guess less than 8 miles once you're on I-4.
Good luck.