This clever dude worked out a simple mod for the Optimus Crux that enables it to be used with a piezo igniter:
http://www.youtube.com/watch?v=RCJ9xrI8nd0&feature=youtube_gdata_player
The mod involves using the optional igniter from an MSR Superfly stove.
I'm going to give this a try once my Optimus Weekend HE arrives together with the bundled Optimus Crux burner.
With this mod, it even continues to fit under the gas canister!
Nifty!!!