Apparently the way to deal with this is to do a prehardener step then develop as E-6. If you don't preharden it, the emulsion just comes off.
Look at:
www.photosmith.ca/Library/Photography FAQ.pdf

under the section "Infrared processing in E-6 chemicals" (quite a way down, page 111).
It details how to process IE (EIR's predecessor which had to be processed in E4 long after all other E4 processing had stopped) using E6 chems without destroying it. This will work with old E4 film too as the only difference is the spectral sensitivity.