I have read on the H.A.M.B. site about these type of bushings squeaking, does the instructions say anything about greasing them?

The original bushing has the inner and outer metal bonded to together. The inner bushing is held tight to the axle or frame and the outer shell is held tight to the arm. You get some control of movement from this setup, sorta like a built in shock absorber. The poly design will be looser compared to the OEM, but will function as a bushing just fine. And if the fit is tight enough to squeeze the poly, it will function just the same.

Joe