IBL is a really wide umbrella term, nowadays at least. I strongly suggest browsing the Academy of Inquiry Based Learning website. They have videos for many of the talks at the R.L. Moore conferences, such as this one that seems to be about "larger" classes. The canonical text on "Moore method" may have some ideas for your larger classroom situation, but I think that you are right that there are not enough resources available.
Looking at the physics literature may help, because a lot of the "flipped" classroom enthusiasm recently comes from that direction. The videos from Sanjoy Mahajan's class on MIT's OpenCourseWare have some very interesting ideas that are closely related to IBL, for instance.
Finally, I would say on a personal note that just trying ONE activity that has the students trying to grapple with their own 'construction' of something is worthwhile. Surely you have one day that you can set aside for some activity that they can do in small groups that is 'inquiring'. See how it goes, get feedback - and be honest that they are doing a service to your future students, to make 'lecture' feel less like, well, lecture. I think many will respond to that.