MAKE SURE CUSTOM TEXTURES ARE ON by opening dolphin, clicking "Graphics", going to the "Advanced" tab, and checking "Load Custom Textures"

1) Rename your desired trail to this:
tex1_128x128_97d28a1503290c1a_14.png

2) Open the P+ Folder and place this image anywhere within User\Load\Textures\RSBE01

3) You're done! :)

