How do cash flows fit into a DW model?

I'm in the very early stages of planning our DW, but given we're a financial firm we have monthly actual and projected cash flows going sometimes over 15 or more years. They're saved in a table with the account code, month, year, then income and expense so it's nothing too complex.

Since we often calculate IRR, NPV, and other metrics on the cash flows at various points in time I really need access to the entire cash flow model for every account at least once a month.

Thanks for any pointers...

Sam