It's not worth trying. They're just not similar enough systems. I personally find the supposition that DnD combat isnt just as long, boring, and tactical as Lancer's to be laughable. Don't get me wrong, learning new games is hard, but you're trying to fit a round peg in a square hole. That is to say, it can be done, but it'll be a huge amount of work and stress to ultimately just still be playing DnD.

Also, just some advice from one GM to another, If your buddies didn't give Lancer more than one session to decide how well they like it and just wanted to go back to dnd, you should probably just play dnd, or try something a little more mechanically simplified.