Actually I tried when I installed the CM9 on my L3, but i couldn't get it to work either. But the good news is that you could install one of these custom ROMs in your phone with guarenteed working of USB storage.
I have tried them both and it works. They are both are built on CyanogenMod 9 for L3. So, they are better than the original CM9 with lot of tweaks and features alongside kernels, of course with minimal bugs. So, give it a shot.