What you really want is to see great chemistry between the ladies first. If they are into each other, implying they "trust" each other, virtually all other activities with you will be a natural extension. Ideally, they will get off on sharing with each other MORE than "working" just to get you off.
Not a bad idea to set the tone with some beverages (in moderation) and chatting clothed for a bit at first to settle nerves and build rapport. Keep it light and funny. Don't make this out to be some epic fantasy moment, even though it totally is!
At an appropriate time suggest they kiss, or explore each other's bodies a bit. That gets the clothes moving in the right direction - down onto the floor.
Next, no script necessary. Just read the room and do stuff that will them feel good and ask for stuff that will make you feel good.
Caveat: You need to decide if a "boundaries and limits" chat it necessary before the skin-to-skin stuff starts. Nothing can kill the mood faster than trying something like anal only to see one or both freak out.
Also, as with any BCD date, I suggest keeping some bottled water in the room, a few hand towels, and other stuff like extra lube. And be sure to lay out extra towels in the bathroom along with other "girl" products like tooth-paste and brushes, clean hairbrush, etc.
Life is good
The Cat