There are two parts to copyright liability: civil and criminal. TL;DR: both cases are criminal offences, and it is illegal to break the law even when you are paid to do it.
In the USA criminal copyright infringement requires a deliberate act to infringe copyright for commercial gain. Both of the scenarios meet these requirements.
In the UK (and probably the rest of Europe) criminal copyright infringement includes
possess in the course of a business an article which is, and which you know or have reason to believe is an infringing copy of a copyright work with a view to committing any act infringing the copyright.
Again, both these scenarios meet this requirement.
In the first scenario you are acting as an employee, so you don't have any personal civil liability for damages; that goes to your employer. However you still have, at least in theory, criminal liability.
In the second scenario you are your own employer and so have both civil and criminal liability. Your client will share some liability as they have provided inducement to break the law.
The best way of dealing with the first scenario is to point out to the boss that he is ordering you to commit a crime. Cite the law in your jurisdiction and the penalties for breaking it. Do this by email so that you have evidence of having told him, and take a printed copy of the email home with you just in case (if your boss isn't above criminal copyright infringement he may also not be above tampering with evidence). If you are in a big company then a CC to HR might also be indicated. If the boss is the company owner then you are in a stickier situation; your best option is probably to perpetuate the evidence as above and start looking for an employer who doesn't break the law.
The second scenario is simpler: just refuse to do it.