I bought a US car and imported it into Canada where I had to add "daytime running lights" so my experiences may apply. I'm presuming that the NSX ciruitry for Canadian DRLs is somewhat similar to the OEM Euro foglights.
I did some research on whether I could add "foglights" ...either the OEM ones or aftermarket...and on my US car, unlike the 6-CD changer option which seems to have come partly pre-wired and the mounting points in place, there didn't seem to be either the "controlling circuitry" or the wiring for the DRLs/foglights.
The "controlling circuitry" is a module that accepts inputs from various sources in order to determine whether the lights should be on or not. For example, the DRLs are normally on if the ignition circuit is live but if the headlights are turned on or if you engage the e-brake, the DRLs will go off. This may or may not be the same for Euro foglights. I don't know what SOS offers .. maybe it just includes an on/off switch for the lights to make it easier.
To make a long story short, I gave up and just wired some aftermarket lights to a relay which turned on whenever the ignition circuit is on. I have been meaning to add another relay to turn them off when the headlights come on (to avoid blinding oncoming vehicles at night) but haven't gotten around to it.