You are going to absolutely love the new programs.
Install TxRaw - just needs a double click to associate RAW files.
Double click any raw and it is automatically copied to the clipboard. Simply paste it into your paint program. No pal conversions required. Paint it the way you want and save as a 256 color BMP file.
Now, unzip FlyRawGui to it's own folder. No install necessary.
Open FlyRawGui and choose convert BMP to RAW, browse to the file you just saved, click ok/open and viola, conversion to ACT and RAW complete.
Now go grab c-pod and unzip it to its own folder.
Open the bin in c-pod, replace the texture and you're done.
Alternately, binedit now does texture replacing too. Check the menu and it should be pretty intuitive.
Any problems or questions, let us know.