My understanding (and please verify) is that they are one in the same...1CC (volume meaning cubic centimeter) is = to 1ML (volume meaning 1 milliliter).
So - you'd simply take 1/4 CC 2x weekly (or Every 3 days or whatever you were looking to split the amount up to).
Now if you have an insulin type needle that is says total volume is = 1/2 CC, then you would fill it halfway (likely to be expressed in "units" on the insulin syringe). Key thing to me is, what is your syringe expressing it's measurements in? CC's, Units, or ML's?
Let me know if that helps any.