It will work but you'll need to be careful with it. A one hour fast charge on that battery would require only 0.2A so you're more than doubling the recommended current feed. On one hand they're NiCd cells so they take abuse better, on the other hand they're generic industrial Cadnicas as opposed to racing-bred high capacity cells and probably don't like charge rates that high.
Set it to 6 cells and go. Monitor temperature and make sure it doesn't charge any longer than 20 minutes. Expect a noticable spike in your discharge characteristics but shortened battery life if you continue to use 0.5A. If you toast it, extras are cheap enough from eHobbyAsia.
