Forgive me if you already know this but IBIS models are not accurate device models. They are roughly accurate models of devices with fairly accurate models of their input and output load and source impedances. <http://en.wikipedia.org/wiki/Input/output_Buffer_Information_Specification> They are mostly of use in Signal Integrity analysis and are not really intended to be used in device level simulations. What you can do is read the IBIS file and manually extract the IO parasitic lead inductances, resistances and capacitances (per-pin parasitic info (R_pin, L_pin, and C_pin) defined in the [Pin] section) and then convert them into spice models of each device pin. There are very few - if any - IBIS to spice converters available outside of the commercial proprietary simulators for the more recent IBIS file formats: <http://www.thedigitalmachine.net/ibistools.html> Most only support up to 2.0: <http://www.intusoft.com/utilities.htm> Similarly .pkg files only provide more specific detail about the pin parasitics and contain no behavioural device level information. For most devices there is so little device level information in the IBIS file that simulation is often reduced to simply modelling what happens as each individual pin (or maybe a bus) drives a signal out and/or receives it after propagating across a length of PCB trace modelled as a transmission line. Being able to use IBIS files would be great but they may not give you the information you are expecting. :)