It would put Warren Steven in an episode of the only 1960's Irwin Allen series he didn't do a guest spot on. If they Kelvans needed a ship to get them to Andromeda, then I'd put it in the 3rd season when the Jupiter 2 was in space a lot more. So it could be a mix of serious and silly, especially if we're talking early season. Serious in tone to satisfy Guy Williams, but with wenough blank space in the script to keep Jonathan Harris happy. The guest cast would be a lot smaller, owing to the lack of funds. I could even see Irwin making the Kelvins energy beings who inhabit the Robinsons. That way - NO guest cast (or maybe one voice artist). Just the regulars being controlled. I don't know, I envision it would wind up being a lot like the episode Target: Earth.
I don't know if the Kelvans would find the Jupiter II useful to their mission. Wouldn't it take millions of years to reach Andromeda? Besides, I would expect Rojan to trash Robot immediately to get it out of the way, and that would ruin half of LIS' (alleged) charm right there. Now, if the Kelvans crash-landed on Altair IV (Morbius' planet in FORBIDDEN PLANET), that would be an eye-opener. Not the least of which because you'd have Warren Stevens x 2. Come to think of it, it would be interesting if the Jupiter II accidentally landed on Altair IV instead of the C57D, or maybe alongside of it. You'd get to see Robbie the Robot meet Jupiter II's Robot. And maybe Major West (Mark Goddard) could get the hots for Altaira "Alta" Morbius (Anne Francis). And it would be hilarious if Dr. Smith (Jonathan Harris) were to have a close encounter with the psychic manifestation of Morbius' dark side. Oh, the pain!
Well, if you're putting the Kelvans on Lost in Space, you must immediately make them less powerful than the Trek version. As for the distance the J2 has to travel, the Irwin Allen Universe is much smaller than the "actual" universe. It would take about 7 hours to get from wherever they are to the next galaxy. And back. No, the women wouldn't be turned into block, that would mean Irwin would have to create new props. They would simply be demateriialized and brought back at the end with no mention as to where they were sent. The Kelvans wouldn't have a belt device, they would just point their fingers. ELECTRONIC POP! Girls gone. John Robinson would defeat the alien leader by engaging in a sword fight with him.
Stolen? It was another Fox production. I heard some of the sounds we associate with the Enterprise bridge in an episode of The Twilight zone that predates Trek.
I suppose we could have had a scene with Guy Williams' character together with Kalinda in his quarters (to get Rojan into his jealous rage), with the robot standing guard at the door, ready to yell: "Danger Professor Robinson! -- Here comes your wife!"