I bought a set of 4.5" headlights planning to put them on my Kawi 900. Never did it, now I want to do it to my Valk (but won't happen for a while...long story).
I bought a relay wiring kit for a dual H4 headlight setup from this guy:
http://www.easternbeaver.com/You (and I) will probably need to fabricate a mount. I would think a chunk of metal bolted to the OEM headlight mount would be the simplest, with two holes drilled wide for two headlights.