First
off, you'll need to know how to identify the custom tone. There's two
ways- either with the file itself, or with a Sim that's using it.
From the skin's file, you want to select "Skin Tone XML" from the Resource Tree (top left field by default).
Select the item that appears in the Resource List to the right and the
bottom field will populate- you'll want to be sure you've got it set to
the "plug in" view. There are tabs at the bottom of the screen that can
be used to toggle the view.
What you're looking for is the "family (dtString)". This is the string you use to assign the skin tone to a Sim.
It may be easier to ID if an existing Sim already has the desired skin
tone. It doesn't matter which neighborhood it exists in as long as you
know where to find it.
Bring up the neighborhood and find the Sim. Do this by using the Sim
Browser found under "Neighborhood: Tools" or via Sim Description,
whatever is easiest for you. Once youve located it, click on the "More"
tab and choose "Open Sim DNA".
The Sim DNA page contains fields for the Dominant and Recessive genetic
traits. The Dominant traits are the ones that appear on the Sim. The
"Skintone" field is the skintone that appears on the Sim- Simply
highlight it and copy it (Ctrl C).
From here, it's just a matter of finding the Sim you want to alter and
replacing the existing value. Once you've replaced it, do not forget to
click "Commit" and save. The next time the game loads, the Sim will
have the new skin tone The changes should be immediate but if for some
reason they do not show right away, have the sime go to a mirror and
choose "Change appearance", this should kick the changes into effect.
It's really quite easy once you've done it a few times.
And, just a reminder, when using SimPE, it's always a good idea to back up your neighborhood prior to any changes.