XDA Developers have finally managed to crack the custom background on all tabs of the TouchFLO 3D on HTC Touch HD.

Once you download and install the cab to Device, you will be prompted for a restart after which the custom wallpaper image you choose to set as background will be valid for all tabs of TouchFLO 3D.

In case you want to revert to the previous state, just uninstall the cab from Remove Programs inside Settings. For those of you who still want to see the default TouchFLO 3D wallpaper while having this tweak installed (installing will set a black wallpaper), you can grab it here.