Functions passed as values should work like this in all CFML engines.

FunctionTest.cfc

<cfcomponent output="yes">
	<cffunction name="getF" output="no">
		<cfreturn function(a){ return a+1;}>
	</cffunction>
	
	<cfscript>
	function test2(closure1=function(a){ return a+1;}){
		return arguments.closure1(4);
	}
	</cfscript>
	<cffunction name="test" access="remote">
		<cfargument name="a" type="any" required="no" default="#function(a){ return a+1;}#">
		<cfset var b=function(b){ return b+1;}>
		<cfscript>
		c=function(d){ return d+1;};
		writeoutput(arguments.a(0));
		writeoutput(b(1));
		var a=getF();
		writeoutput(test2());
		writeoutput(c(4));
		// output of FunctionTest.cfc?method=test should be 1234
		</cfscript>
		<cfabort>
	</cffunction>
</cfcomponent>