what happens when you try to install the backup manager pkg's? Do they install and then fail to run, or do they fail to install in the first place? Please provide more detailed information on your problem
Yes, please more info Some things to note - don't take offense as these might be simple mistakes
Don't forget that you'll need to boot up the USB JB every time you want to use the BM - even with installing pkg and playing homebrew.
The PKG should be on the USB stick, and it should show itself as an 'install package files'
If you've installed CFW you'll need proper CFW made BM [note I'm not totally familiar with the new BM and the CFW] - the same goes with the new BM - which are made for CFW - not sure if they would work with USB JB.
Please provide some more info so we can hopefully help you out. Thanks.