Softimage, one of the FX software powerhouses, has an article about ILM's work on The Mummy Returns with special emphasis on the use of Softimage 3D in different sequences.
Softimage has been used for a long time at ILM, dating back to some of their first CG FX work like the original Jurassic Park. The article discusses the different uses of Softimage 3D, like rigging and used alongside the mocap data. The article can be found here:
It has also been rumored that ILM recently acquired a bunch of XSI licenses (180 or so), along with new Compaq Digital servers.