Water Heater

[Rolebama]

I bought an aluminium unit for my last car (306 DT) with four glow plugs in it. I would like to fit it in my 406. I have read about removing trim bits and lifting carpet in passenger footwell and looking for a grommet/bung, but what is the approved way of getting the wires through the 'front bulkhead'? I have a 'normal' size switch blank and a 'half-size' one next to my HRW switch on the dash, is there a choice of switches, or do I just grab the first one that comes along? (I would like an illuminated one, but not necessarily another HRW one as that would look 'tacky'. Thanks.