Updated Network driver Dell 4220 Projector

I have this projector that is a Dell 4220 that I am trying to figure out how to update the drivers on it for a mac computer. Currently we have it set up on the network, and it can be reached via IP address. Once we go to that page, it has a driver that can be downloaded for PC or Mac. We now have some Mac computers that are OS 10.7. The driver that is there does not work for OS 10.7. We have some computers with OS 10.6.8, and those work with the projector. How can I get a driver for OS 10.7? I couldn't find one on the website or a firmware update to update the projector. The projector came with a driver that works with 10.6.8.