I know you can set the chipset to ad-hoc mode by
/etc/init.d/wifi --mode ibss
However the kindle os still doesn't allow connecting to ad-hoc, so you have to us iwconfig
iwconfig wlan0 essid yournetworkhere
I don't know if security (wep/wpa) is supported by the chipset or not. I think the reason they don't have ad-hoc support is that wep doesn't work with ad-hoc. I also don't know if this method is for creating an ad-hoc network or joining one. I haven't tested it.