Technically, no. The ICE is NEVER off in an HCH2 while driving (like it can be at low speeds with a Prius).
When possible, what happens is the ICE closes the FUEL INTAKE valves shut (exhaust ones too, I think [to reduce pumping losses]). This is the mode where the ICE is turning (at 1000-1100 rpm), but is using ZERO fuel.
It's cool for short distances at lower speeds, where you can get the rpms down to 1100. That's like a magic number.
PCK is right about how to go about it:
(1) Let off the gas ENTIRELY to get down to 1100 rpm when you are already at or just above 1100 rpm.
(2) Watch the instant MPG meter peg 100 MPG
(3) Then and only then ease back on to the gas very lightly to remove the regenerative charging and get 1-3 bars of assist.
I can only seem to get 2 bars of assist before losing this state. So I just stay at 1-2 bars as long as it'll hold or until traffic makes me speed up or slow down enough that I lose the mode. You know you've lost this state when the instant MPG meter suddenly drops

.
This works at several different lower speeds, as long as you can be very near 1100 rpm at that speed. The CVT probably contributes to this being possible at several speeds (like a 5-speed transmission might allow you 5 different speeds to try this with).