One of the Developer still work on the Apk so that version work on ICS !!!
Hello i created a guide in a Italian forum (i'm not italian but i live here), how to use a usb otg...and if you know italian or you want to see that guide that is it:http://www.androidworld.it/forum/firmware-e-modding-sony-ericsson-xperia-arc-s-24...
If i flash this kernel over Siyah, will i still be able to boot both of my ROM's?
Or will my secondary will be lost and i have to flash a new secondary?
No you don't need to reflash the secondary rom ;)