The million dollar question. You can go about this one of three ways. Either use Spin's modified APE, editing in Winhex, and to extract. Here I will post the pros and cons of each along with links and tutorials.
Spin's Modified APE
Works with DD, MM, and most of Microsoft/Blue Fang Official Downloads. Though it looks complicated, it's easier than you think.
Download at:
Spin's Modified APE
Pros:
* You can easily screenshot the plaque and icon when working in APE.
* APE gives your animal its own ID# so it doesn't overwrite original animals and you don't have to extract and upload the pics as you do with extractions.
* With a little tweaking you can get APE to bring up plants and other previously non-accesible objects.

Cons:
* It what save stat changes, descriptions, etc in a modified version. I have to switch the modified config.ztd back to the original config.ztd. Then I have to load my animal up into the original APE for the stats and other info to save.
* Even the modified APE forces you to edit the uca manually. In dinosaurs there's the egg hatching bug, the MM animals sometimes appear invisible and show programming is non-existent.
Extraction Tutorials
Works with DD, MM, CC, and all of Microsoft/Blue Fang Official Downloads. Though it looks complicated, it's easier than you think though some parts still confuse me.
Available at:
Here and about every other ZT site. Just look below.
Pros:
* Doesn't have any advantage over Spin's APE that I can think of except that you can extract CC animals.
Cons:
* Extraction is fun, right? Copy, paste, copy, paste..... It can get tedious.
* You have to download all images off ape and them upload them into a new ztd or risk overwriting the original animal.
* Plaque? Icon? You'll have to get them elsewhere.
* Still have to edit the uca manually. DD you mainly have the egg hatching bug, and in MM you have to add programming for water depth, salinity, murkiness, and show programming.
Editing in Winhex
I gather it works with DD, MM, CC, and all of Microsoft/Blue Fang Official Downloads. I've never tried it before. If anyone has I would love to hear your opinions on it.
Available at:
Here. Just look below.