There's just a wee bit more to it than that, but it's not rocket science. You will need to run a new dedicated circuit for it that's not shared by anything else and on it own breaker (you might consider paying a certified marine electrician to do that much)...the rest is just plumbing, not that much different from installing a new manual toilet. Just be sure to READ and FOLLOW ALL the installation instructions.
What you may not know is that you may not have to buy a complete toilet...that if your bowl, seat and lid are still in good condition, you can go with a "conversion" (everything but the bowl seat and lid)...yes, your bowl WILL fit any that you'd want. IMO the Raritan SeaEra would be your your best choice...Practical Sailor named it "best budget buy" in a comparison of all the major macerating electric toilets. Available in both sea water and pressurized fresh water versions. Check it out here:
SeaEra Conversion Kit And I'll be glad to answer any questions, here or one-on-one.