Hello Little,Reading SC's post reminded me of my own daughter who has been known to faint at the thought of an IV. 
But let's take it from the top - I have had Go-Lytely - nothing lightly about it - LOL. I have read a lot of people prefer a straw but I do better filling the glass with the fluid and chug-a-lugging it without thinking about what it is - just down the hatch. With a straw you have to breath between taking sips of this sparkling beverage so it prolongs the anxiety.
It is not thick or nasty so much as it is just a lot. You may try putting it in the freezer to make it more like a slush if the straw is your choice.
Once it starts working stay close to the bathroom unless you are a sprinter.
AS far as the IV, are you any good at imagery? I always take my mind to another place, a warm tropical island and I tune out the play by play description by picturing my happy place in my mind where no IV needles exist.
Be upfront with your nurse and ask them to start your IV using Pain Ease instant, non-drug, topical anesthetic or what ever product they have that does the same thing.
As long as the anesthesiologist will be with you ask for this person to start your IV - they do them all day long ! Some clinics use Propofol which I have had for another procedure. I was on a Propofol drip for 24 hours and all I remember is a word here or there but mostly I was pain free, not anxious and sound asleep unless the Dr. would shake my shoulder and call my name.
You will do well and the prep is really not so tough until your half way through the jug of juice.
Kindly,
Kitt