The 2 piece rubber are the easiest to install when the engine is assembled, I have done it in the car a lot. Just roll it in place. The rope can be done in the car, but it's best to use a tool made just for this.
Summit sells the Lisle tool, it available other places also.
Lisle Upper Rear Main Seal Remover and Installer Tools 27000
The best way to do the rope is when the engine is apart. It can be done in the car. The key is fitting the rope to the cap first, then using the tool to install it in the block, then fitting the other half to the cap again. There is a tool to fit the seal in the cap, but you can use a large socket also.
Press the seal in the cap, use the socket and lightly tap the socket with a hammer to seat it in the cap.
When the engine is assembled loosen the main cap bolts to give you a little more room to install the seal.