Hi, I've been giving Sub-Q fluids to various cats of mine for years now. Currently Bob and Sydney get some every day.
I get the supplies and equipment from the vet's office (perhaps something like a medical supply house would have them cheaper?): the fluid bags themselves (I get a case of 12 at a time), the needles (I get them in boxes of 100 at a time), and the fluid lines to connect the bag to the needle and have it running in a steady stream (I use one line every two bags, so I get 6 more lines each time I get a case of 12 bags).
As for how and where to hang the bag, it needs to go somewhere high enough that the fluid will run down. I hang it from a bent coat hanger hook and then hang them up on the shower curtain rod.
One thing I learned early on: it is MUCH more economical to buy fluids by the case than to buy one bag at a time. When I started out, I was paying around $10 for a bag, but then I found out I could get a whole CASE of 12 bags for about $35. Ever since then I've always bought it by the case.
Giving your kidney-challenged cat fluids will help keep him going much longer. Best wishes!
I meant," said Ipslore bitterly, "what is there in this world that truly makes living worthwhile?"
Death thought about it.
"Cats," he said eventually. "Cats are nice."
-- Terry Pratchett, Sourcery