I was able to do this today after finally getting an Android x86 image working in VirtualBox. I followed
this guide. Especially take a look at the part titled "Connecting the Android x86 VM to AVD and Eclipse".
In the virtual machine settings, under network I have it set to "bridged adapter" which lets me select my host wifi adapter. Then go to a shell in Android (alt+ctrl+f1) and type netcfg. Open a windows command prompt and navigate to the platform-tools folder under your Android SDK. Type adb connect <IP from netcfg under eth0>. Now when running Processing you should be able to get your sketch on the VM by using "run on device".