Disney to Port: I-4 East (sometimes the general I-4 sign comes first) to 528 East. Get off of 528 at its exit 9 (Tradeport). Left and cross under. Get into middle lane. Required right onto McCoy. Next light about a mile later is 436 (Semoran). Right, cross over, get back onto 528 East.
Port to Disney. 528 West. Get off at exit 10 (436, Semoran) to go north. Left at first light (Frontage, becomes McCoy). Next light take a left (Conway) and immediately take another left onto 528 west again. At end of 528 take I-4 west (southwest).
In both cases watch for toll signs on 528 and in some cases you must take what looks like an exit ramp to pay toll in cash.