Why don't you do your conditional text column in qlikview object itself (refer to sample attachment). then nprint easy to capture the format.
try to put like below in your expression (measure filed --> under text color)
if you really wanted to do in nprint custom format like below
When you want to format your cells in XLS you must use "Excel Conditional Formatting" for cells you want to apply collors to!
see screenshots (i did them quickly in Excel, but you would have to do it oin NPrinting designer - template editor and conditional formatting will be applied to the tag representing your number , like: <nodeXX>: