my father in-law says that they temper there hawk handeles and ramrods by soaking in anti-freeze. anyone out there used this method

I have never tried that method. I doubt it has the same effects as heat tempering bow bellies.

I have spoken to a guy who makes gun stocks and he said he does that but in an effort to stop checking. I looked into it for a table top I was going to make from a large log cross section. there is a chemical that is very similar to the one in anti-freeze that is used to prevent wood checking. it somehow gets into the cells and replaces the water, making the cell stable. This chemical is close to anti-freeze, but it is not the same and from the research I did it seems that the anti-freeze is actually useless for this purpose. I do not have any experience with using either and you may be talking about something else.

Anti-freeze is basically glycerin and alcohol(Glycol)...at least the old stuff was.  Like on snake skins(a curing method) the alcohol carries the glycerin into the cells and displaces the water then the alcohol evaporates and leaves the glycerin in the cells. I can see how it would help prevent checking but I wouldn't want to handle it on a regular basis.

I've never heard of that with bow wood.

This is a very common misconception.

Normal antifreeze contains ethylene glycol, which is poisonous.  RV antifreeze contains propylene glycol (not poisonous).  Neither stabilizes wood well, and using ethylene glycol can be very dangerous depending on what the intended use is.

Green wood is stabilized by soaking it in polyethylene glycol (PEG).  This displaces the water in the wood cells and prevents drying cracks as the wood dries out.  That's it.

You can buy PEG 1000 at some of the bigger woodworking supply places, but I cant see a use for it in bow making.
Great for wood turners though if you want a piece that will always feel waxy

Thats the stuff!
Thanks Jeremy.
It is also very expensive if I remember right.