Concerning the Family Tax Cut, how can I reduce the amount of income splitting with my spouse? It's not in my favor to split the maximum amount!

My non-refundable tax credits exceed my Federal tax after income splitting, so they're basically 'going to waste'.  Thus I'm loosing several thousand $$/year.  I need to split a lot less than half of my income off to my spouse, so I can take full advantage of my non-refundable tax credits.