During an ILS approach, the ILS/DME is autotuned by the FMS and the ILS/DME distance is displayed in the lower left corner of both PFD. The 'nav switch' on the EFIS secondary control panel must be set to ILS.
Setting the switch to VOR will enable you to tune VOR/DME stations using the VOR frequency controller, but not, as far as I'm aware, ILS/DME frequencies.