I use the canned GM quite frequently. I mix my lye with water and add the GM to my oils and mix well before adding my lye/water. I use a bit more than equal parts water to my lye to dissolve the lye. I add the remainder recommended amount in milk. I don't dilute it at all. You can also use powdered GM or BM. I just dissolve it in some of my water and add the same way.
I picked up some evaporated goat milk.
[FONT="]How should I mix it with water or should it be mixed?[/FONT]
[FONT="]Can it be added at trace all or part?[/FONT]
You can do any of the above, actually - in the end, how you do it all comes down to personal preference based on how things turned out for you.
Back when I used to use the canned evaporated GM, my preferred method was the same as what Shari mentioned above- I'd mix my lye with water (more water than lye), then add the rest of my 'water amount' as evaporated GM into my oils (just after adding in the lye solution).
I like to use fresh and/or powdered GM nowadays because it gives me a much lighter-colored soap (off-white). The canned always gave me darkish-tan soap.
I do the same as Irishlass - pulling out some water from my base (normally 100 gm to keep the maths simple) and use it for all my additives (powdered GM, aloe powder, clay, edta, etc). It helps ensure that it's fully mixed and re-hydrated. Then I add that into my oils and mix fully before bringing in my lye solution.