That would be another viable option, with a slightly different connotation.
"De liker ikke dem" = "They don't like them" ...but someone else. The focus is on the object.
"De liker dem ikke" = "They don't like them" ...focus is on either the verb itself or the negation.
Based on Deliciae's response, it sounds like you wouldn't say, "They like not them" unless that's only the beginning of a sentence that would be followed by further clarification. For example, "They like not them, but us." When it's just a complete sentence by itself, it makes more sense to say, "They like them not." What comes to mind for me is the phrase, "He loves me, he loves me not."
I hope I got this right:
“Their bosses do not like them.” = “Sjefene deres liker dem ikke.”
“Your (pl.) bosses do not like them.” = “Sjefene deres liker dem ikke.”
“Their bosses do not like you (pl.).” = “Sjefene deres liker dere ikke.”
“Your (pl.) bosses do not like you (pl.).” = “Sjefene deres liker dere ikke.”
I was just thinking (overthinking?) about this sentence, and I''m thinking that if the sentence had been "They are not liked by their bosses", we would have said "... sjefene sine". I love how the word "sine" avoids the English ambiguity present with "their" (their own bosses, or someone else's bosses?), so I'm a little disappointed :-) in "sjefene deres" here, which is even more ambiguous than English (it is: your bosses? their own bosses? Someone else's bosses?). So I've been wondering if we could say "Sjefene sine liker dem ikke". I realize that here "sine" is referring to "dem" which is later in the sentence, but still, the meaning of "Sjefene sine liker dem ikke" seems clear, so I am wondering if we can say that.