Looking to create a tekkit texture pack

[SirLucien]

So I understand how to Create a texture pack for Minecraft, but with Tekkit, it appears that some mods reference the .png file inside the zip folder for the additional blocks and items in the mod, it isn't necessarily pulling all textures from the texture folder.

So my question is, will the properly named .png file in the texture folder override the .png in the mod zip? Does the .png for a mod have to reside in a certain place of the texture pack zip so it knows to ignore the original and use the one I created?

Thanks for any help on this question.