I have designed in the i.MX6 Solo Lite in my board. I need to run SI sims on the USB traces. I have downloaded the IBIS file, mx6sl_416mapbga13x13_autmtv, from Freescale. I don't think the IBIS file implements a model for the USB pins. It looks like the models for the USB D+/D- pins are listed as "NC". Am I reading that correct?
yes, you are right, not all i.MX6 ibis models have usb,
for example i.MX6SDL has
IMX6_DL_S_IBIS : i.MX 6DualLIte and i.MX 6Solo IBIS File.
Probably you can use it. In general it is sufficient
to follow usb layuout guidelines in below document
Hardware Development Guide for i.MX 6SoloLite - User Guide