European PHEV

Hello,
I'm sure there is already a topic about it or at least some post, but I haven't found them, sorry.
I'm actually converting a prius into a PHEV with Ewert Energy HEM and I'm wondering; because I already have the ev button once I've splice the "Try-EV output" to the wire in the pin #27 of H14 (where in the american prius there is nothing), what should I do to the PHEV, EV and Hybrid button input? It's said in the instruction they have to be momentarily ground to change mode. I do not think strike the wire on the chassis while driving is a good idea... Do you have any tutorial about it?
Thanks