I've found a way of getting remote wireless radio HSS using RF-602s. It's a bit invloved, manual only, but it works
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I for one would like to know how
I thought posting that comment might be a mistake

Well, this is how it works with my Canon 580EX guns, four of them, with four RF-602 triggers. Other guns/triggers may works differently, or not at all.
First you need one of these:
Which is a simple optical slave (from
www.colinsfoto.co.uk ) plugged straight into the RF-602 transmitter and fitted so that it picks up the flash from any gun set to high speed sync. I've since got a little 270EX for this purpose, with a neat custom made enclosure (actually half of an E45 skin cream bottle, which slips on Stofen-style). BTW, you can also use the same workaround to do radio-triggered second curtain sync - see below
Then you need to prep your remote flash guns, by setting them to slave and then firing them in HSS mode using a master gun set to whatever manual power output you finally want to use. Then you plug them into the RF-602 where they retain whichever firing mode was last used, in this case HSS. Now you're ready to shoot.
With the flash on camera set to HSS (mimimum power is fine) the optical slave picks up the HSS flash which goes out well ahead of all the other triggering signals. Which trips the transmitter, which then triggers the remote receiver, when then fires its remote flash which of course now puts out a HSS pulse. There you go.
It works for me, though sometimes one of the flashes doesn't fire - maybe once out of ten. I have no idea why, checked everything loads of times, but I guess neither the flash nor the triggers are supposed to work like this. So it's up to you - I'm not recommending it, particularly as you can get remote HSS using the regular IR system anyway.
However, the radio remote second curtain sync is not available in any other way with the normal Canon system and that works 100% reliably. Just set the remote guns as you normally would on the RF-602, and the on-camera flash to manual second curtain sync. Sweet
