New day, new tweak in Cydia: SwitcherPlus. SwitcherPlus allows the native multitasking ‘switcher’ feature to also be used in the lockscreen mode and it also allows you to customize it. Devs are saying that some extra features will come in future releases, so stay tuned.
You can find SwitcherPlus for free in Cydia via this repo: http://www.switcherplus.com/cydia/spbeta1.0