The following will only work with CF11; earlier versions do not include a new enough version of POI. This example will color cells A1:A6 in red if the value in them is greater than 100. Assume downloadDoc is the object returned by SpreadsheetNew(), after you've filled in the data.
<cfset var poiSheet = downloadDoc.getWorkBook().getSheet("Sheet1")>
<cfset poiSheet.setFitToPage(true)>
<cfset comparison = CreateObject("java", "org.apache.poi.ss.usermodel.ComparisonOperator")>
<cfset rule = poiSheet.getSheetConditionalFormatting().createConditionalFormattingRule( comparison.GE, "100.0", javacast("null", ""))>
<cfset patternFmt = rule.createPatternFormatting()>
<cfset color = CreateObject("java", "org.apache.poi.ss.usermodel.IndexedColors")>
<cfset patternFmt.setFillBackgroundColor(javacast("short", color.RED.index))>
<cfset cellRangeAddress = CreateObject("java", "org.apache.poi.ss.util.CellRangeAddress")>
<cfset regions = [ cellRangeAddress.valueOf("A1:A6") ]>
<cfset poiSheet.getSheetConditionalFormatting().addConditionalFormatting(regions, rule)>
For your own purposes,You will probably want to modify the lines I have placed in italics. the assignment to rule defines the condition under which a cell gets highlighted. The call to patternFmt.setFillBackgroundColor sets the color that is displayed (available colors are given here). Finally, the assignment to regions tells the sheet which cells should be conditionally formatted.