Please read this post http://wl500g.info/showthread.php?t=4145 for download link.
Final 1.9.2.7-7f firmware solves Premium box problems. The firmware itself is just a WL500g Deluxe firmware packaged for the WL500g Premium, so it has slightly different web iface and misses some features, such as Download manager, fancy samba config, etc. It's designed mostly for "do it yourself" persons and features ipkg support, etc + everything we've in my firmwares.
Please note: my mission is not the tons of features, but router stability.