Super easy, barely an inconvenience. Since, as with all Star Wars films, Lucas was mostly just making it up as he went along, he got so caught up in adding cool new stuff that he didn’t get around to any of the essential stuff until RotS.
That’s not to say the rest isn’t worth watching, just that you wouldn’t be lost without it, or at least the case for TPM, as the Machete order proves. However, as any 3-in-1 Prequel editor will tell you, you should start with the end duel with Darth Maul and Obi-Wan promising to train the boy. I mean, sure, it’s just as unnecessary as the rest, but it’s such an amazing scene and the ending is sorta relevant. I guess now that I think of it, there’s not much reason to include it, but it doesn’t really hurt.
As for AotC, there’s some bits you should probably include. Include the Obi and Ani meeting Padme in her apartment, Obi-Wan discovering the clones, Anakin and Padme spending “falling in love” on Naboo, the three getting captured, and the clones rescuing them. No need for the Dooku duel, since there’s one early on in RotS.
Oh wait. Now it’s just a 3-in-1 edit. Aw well. I spent too much time on this post to delete it. I’ll just try again.
What do you need that isn’t in RotS?
-Introduce Dooku
-Explain the Clone Wars
-Introduce Padme
If you go with a crawl, those first two are covered. You could argue Padme is introduced well enough in the film as is. Just patch everything up with flashbacks to the other two films and you should be good.