We need Cable and the Black Panther to meet up. This should happen naturally within Black Panther, seeing as T'Challa is on his "visit important rulers" field trip, and Cable runs two countries now. And they should very naturally fight, since that's happened pretty much everywhere the rulers of Wakanda have gone. I haven't heard about that happening in Black Panther anytime soon, so I guess it falls upon Cable/Deadpool to do it. And honestly, that would make it so much better.
That way, when the inevitable fight starts, Deadpool can say something about how "nobody can beat the Black Panther." From there, it can go two ways:
1) As Cable is losing - because even technology from centuries in the future is no match for the Black Panther - Deadpool can amuse himself by hitting on Storm, who will cause a huge distraction by making Lightning Roasted Deadpool, allowing Cable to get in a cheap shot and win the day.
2) Cable and Black Panther don't fight. They are, after all, reasonable men. But on the way out, Deadpool - probably out of boredom - picks a fight with T'Challa, shouting "Reginald Hudlin's not here to save you now!" The fourth wall breaking will confuse the Panther long enough for Deadpool to get in some shots, before Storm - with a look of extreme annoyance - creates a whirlwind to toss Wade up in the air, and dump him unceremoniously in Providence's waste areas several miles away.
Ah, Deadpool, you're such a useful outlet for fan frustration.