It all depends!
Are you handy with a spanner and can you raise the car off the ground and keep it there safely to allow access?
Fitting is just a case of getting it in the right place and doing up a few nuts.
If you cannot get the car high enough up on axle stands then it will be difficult to manoeuvre the plate into place (a genuine CatLoc plate is heavy and awkward) and you have to hold some of the bolts in place whilst tightening the shear nuts. Some Lexus garages will fit one for a reasonable sum, try contacting one local to you.
If you do fit it yourself then make sure it is in the correct position and rattle free before taking the final step of shearing the security nuts.
Once the vehicle is high enough, they are fairly simple to fit.