Some options to try:
- You can over-sharpen your textures in photoshop before import, to compensate.
- You can try importing the texture at one size higher than you will use, and set mip Gen Settings to Sharpen10 (or lower), and set the LOD Bias to 1 to use the sharpened mip as the base. Note this can sometimes make for really splotchy mip maps down the chain.
- You can try searching the engine inis or cfgs to look for any anisotropic/triliner/bilinear filtering is happening and set them to lower values.