Officials with Countrywide Financial Corp. are looking to cull more fee income and other revenues from their mortgage assets by setting up their own management fund for residual subprime instruments and by issuing their own collateralized debt obligations for volatile securities. According to the firm’s latest presentation to investors, the mortgage lender’s Capital Markets division pulled in $479 million in pre-tax earnings in 2004 – a boost of 8 percent from the $442 million set…