While you won’t have the control you’d get in AFX or Motion, you can experiment with some generators, effects and transitions available in FCPX. In the Generator tab check out Solids and Elements. They can be modified by Effects. Look at Blurs, Distortion, Light, Looks and Stylize. Play with Transitions in Blurs and Lights. You may be able to adjust the transition parameters to create a frame you can freeze to create a background. Good luck.
John
MacPro 8-core 2.8GHz, 16 GB RAM, OS 10.7.4, QT10.1, Kona 3, Dual Cinema 23, ATI Radeon HD 5870, 24″ TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 3 (FCP 7.0.3, Motion 4.0.3, Comp 3.5.3, DVDSP 4.2.2, Color 1.5.3)
FCP-X 10.0.7, Motion 5.0.6, Compressor 4.0.6
Pro Tools HD 10 w SYNC IO & 192 Digital I/O, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec DSP Monitors, Prima CDQ120 ISDN