Swap textures with Minecraft Mod?

Hey For a few days I have been planning to develop my own small Minecraft Mod. Now I wanted to know whether I have original MC textures for example. Can easily change directly from a sword with the modpack or whether I have to offer a texturepack separately?

Usually you can deliver the right textures with your mod. Whether you are able to programmatically change existing textures (adjust hue, or something) … That will certainly work, but I can't tell you exactly how.

Ok, that's enough for me! That is because I just want to. Pixelate the swords completely!