It depends. If they have a commonly used replacement use the replace_multi.txt file and add the Portuguese equivalent.
It is a list of Latin expressions like the one you see in multiwords.txt, and that I will add one of these days, make a new text file and I will create a new Java rule for Latin expressions.
If they are single words, they should be in a grammar.xml rule and in the spelling.txt.
Add to grammar.xml beginning section:
<!ENTITY latim "ipsis|verbis|lorem|....
Notice that if the rule is too extensive, it may have to be trimmed or disabled by default.
Even with the commonly accepted barbarisms I have added, I had to make more revision work than what I had expected.
Please, do not add an entire Latin dictionary, like this:
Try to limit to the most common words and expressions. Tons is good, but it has to be workable.