Just use a generic blank 6 pin chip in the same package, or create that chip in Eagle...
For example you could use the H11L2 in Eagle, it will still give the impression of what the part is (aka optocoupler) but the pins are defined slightly different and won't simulate if some sort of simulation is necessary... Just hook it up properly as if it's a MCT2E... I don't use Eagle all that much (so I don't know if it will) but if it fights about the VCC or GND nets on the alternative chip and thus won't let you hook them up as if it's a MCT2E, you might be forced to either make a proper one or just use a blank chip so that you can properly connect...
BTW don't shy away from making your own package, you will have to do it eventually, and doing/learning it on a 6 pin chip is a whole lot easier than some other exotic package when you are forced to learn...