try these.
1 way--take a file in the folder,drag it to any folder,open it in MSpaint,or whatever,change it,and put it back in the zip file.but remember to delete the one in the folder you changed!
2--look for "setcolorshift"in the ITEM properties,not the IMAGE properties,and enter the RGB numbers.(to figure mine out,i go to blockland's player editor,click color set in the lower left ,and play with the colors.