Replacing Pickups without back or front plates on an LP

Hi,
This is my first post here but I'm hoping I can get some help replacing pickups.
I picked up this cheap guitar to be my project guitar so I can learn how to set up and repair guitars. The first thing I want to learn how to do is replace pickups.
Here is a link to a picture of the guitar:
I starting taking things apart and realized there is no back plate to access the electronics, no front plate either. The only access is through the pickup cavity or volume/tone knob holes.
Does anyone have an idea as to how I can replace these pickups?
Thanks,
Justin