It will actually activate quicker if disked in ......but i just broadcast mine and let it work. we disk in the fall anyway, so i like to lime in the spring because typically it takes 6 months to alter the ph of the soil. But liming is an investment so as Nike says............"just do it"!! You will reap the benefits later and that is enough incentive.
Since lime can only affect pH of soil that it contacts, it's better to disk it in. It will eventually do the same thing though if you don't. In some cases, such as liming a pasture, you can't disk it in or you would kill the pasture so you have to just broadcast and let the rain wash it into the ground. For a food plot though, if you are disking anyway, why not wait and put the lime out 1st.