Because I'm having trubble getting the horn to work correctly, am considering re-fitting my Moto-Lita non-IVA friendly wheel. Centre hub is non-flexing plastic, so I guess I could temporarily fix some form of covered sponge pad to the centre boss.

Has anyone passed successfully with such an arrangement? Any tips on my proposal?

I used a thin piece of ali plate with 12mm motorcycle seat foam glued to it. this was covered in black vinyl and screwed to the wheel/boss. Looked neat and passed IVA
No wheel mounted horn obviously.

Anything regarded as temporary is likely to fail IVA. Thats if it looks temporary.

a horn switch can be mounted pretty much anywhere, can just be a dash mounted momentary switch.

[Edited on 10-7-13 by loggyboy]

mine passed with a foam pad on wheel , horn button on dash

Well, this was an option, but think I'll follow the recommendation to fit a relay, to power the horn. So I can continue with the IVA-friendly Sierra wheel.