You can take the old chain off any way you please. You can grind it off, beat it with a rock, use an oxy-acetylene rig, plasma cutter, hydraulic bolt cutter, hacksaw, whatever you have available
To install it, you can improvise a means to peen the master link pins (you aren't thinking of a clip type master link, are you?); but I would strongly suggest you not do that. A failed chain will ruin your day in a hurry, and in a big way, as you are probably aware.
If you shell out the money for a good chain press, and take your time with it, you will have the peace of mind knowing that the chain is installed correctly, and safely. Using an improvised chain tool can compromise the chain.
When you look at most chains, you will notice that the pins are "quad staked" That means that they are peened over in four areas (sort of like bisecting the pin). What this accomplishes is that it spreads out the clamping force of the peened pin on the side plate uniformly, and allows more surface area to do so without compromising the integrity of the pin.