I need to replace a brake dust cover. does anyone know where the instructions to do this would be I can not find it ANYWHERE. 17 is 300 f sport.

 

I've never done it on my IS before, but other cars i have and i would imagine its somewhat the same steps. Basically you have to remove the caliper, then rotor and then you should have access to the bolts holding the brake dust cover on. I remember on the last car i did this they were 10mm bolts, 4 of them.
Hope this somewhat helps you and points you in the right directions, but someone that has done it to the IS can confirm its the same would be great!

 

 

Is your car RWD or AWD? Are you doing the front or rear? Isn't the car still under warranty?

Assuming it's RWD and you are doing the front, them the caliper and brake rotor need to be removed.
Disconnect the ABS sensor connector from the back of the hub and remove the 4 bolts. The wheel bearing assembly can then be removed, and viola, there is the backing plate.
Reinstall in reverse order torquing everything down.