You can pop out the wires for the relay (or break them free from the burnt plastic) and plug them directly onto the relay pins. All they are is standard spade lug terminals. They're supposed to release from the plastic- they have a little finger on the side that locks them into the socket. Each could be removed and simply plugged onto the relay. Probably need to tighten each terminal a little with pliers. If the ends are really bad, you can cut off and crimp on a new connector, and plug to the relay.
You can tape the individual wires with electrical tape to complete the temporary repair.
That would fix it until you get a chance to completely repair the fuse box. I've had connection problems with our 88's overdrive in the relay block, and my 87 240 had a headlight relay connector burn up on it as well. Any high-current removable connection potentially can have this happen to it.

Good luck with it!
--
Rob Bareiss, New London CT ::: '87 244DL/M47- 234K, '82 245T/M46-182K, '84 242DL/AW70-100K, '89 244DL/AW70- 212K and I miss my: 86 244DL 215K, 87 244DL 239K, 88 744GLE 233K, 88 244GL 147K, 91 244 183K