You can most definitely dye your seats. But I recommend taking it to a professional to have it done correctly and to have a good seal & protectant on the dye. I bought tan Mercedes Benz seats (in the auction they were gray, I swear, but when I went to pick them up they were tan ?:roll: ) and dyed them black myself and did a good but not thorough job on the seal. The seats looked AMAZING, it CAN be done, but you have to make sure you do everything right and not with haste.
Here's a look at my Benz seats (I sold them and now use a Mountaineer leather interior):