Wrap each section with a rubber mat and grip with vice grips.
NO!!!!! NO VICE GRIPS!!! NO WAY!!
Wrap with rubber---YES!! Wrap each section of the rod with a thin sheet of latex or rubber---wrap from the farrel where they join down approx. 4 - 5" on BOTH sections of the rod
Then get a friend (a GOOD one) to stand directly opposite you. One of his (or her) hands grips one of the sections (on the rubber); one of your hands grips that same section just behind (or in front) of his or her hand. His other hand grips the other section---your hand ----once again---either just in front of his hand or just behind it. Then you agree which pair of hands will twist and pull apart clockwise and agree which pair of hands will twist and pull apart counter clockwise
make sure the directional twisting direction and pull-apart-part of the deal is CRYSTAL CLEAR to both you and your partner, then gently start twisting and pulling apart (pull backwards exactly on the same plane as the stuck joint)
I've done this my daughters and with the wife (now ex-wife) and it worked every time --- I once fought a big steelhead on a 12 ft Loomis and once I got it on the beach, the sections were jammed together so bad I thought that was it for the rod.
Got it into my truck (in one 12 ft piece, sticking through the rear slider) and once at home, used two strips of latex rubber (from a pair of fishing waders) and we got it apart using the above method---a child's hand works well---they get a good grip on a small diameter rod!
The behind-the-knees instructions will also work but that method seems a bit harder to get the directional twist-n'-pull thing going on. Four hands seems to get the job done without breaking anything
I now rub the male sections of my rods against the side of my nose to lube them up prior to joining. I use a whole pile of 4 piece rods now so the lube thing is critical---haven't stuck a rod in many years with that low-tech approach
GOOD LUCK!