(1) Find your Altera FPGA device here: https://www.altera.com/support/support-resources/download/board-layout-test/ibis/ibs-ibis_index.html and get the IBIS model(s) for the pins you are interested in.
(2) Google 'ibis to spice converter'. There are lots of free tools available that can convert IBIS models to a spice model.
(3) Now you can create a custom component using this spice model as a basis within LTspice. Described here:
http://www.linear.com/solutions/4678 (4) Generate an LTspice schematic using your custom component with the IBIS model, and run your simulation.