Hi Al Kondo,
Sorry it took me so long to answer; it's the time difference - I am in the
'country of Oz'.
As to the sample:
The only difficult thing is to know when your cat is going to pee. This is
why I always advocate that every domestic cat should have a litter tray.
Many people think they are so smart; their cat does it in the garden. They
may be lucky - if it is particularly resistant to urinary tract diseases.
Once you can see your cat approaching the litter box, it is a piece of cake!
If you want to get a sample, all you need is to is to be prepared and ready:
You need to have: a clean, sterilized container (your vet will give you one;
I crashed mine so I had to use something else. I use small glass jam,
mustard etc. jars - they just need to be well washed, and I disinfected them
by scorching inside with boiling water.
Next thing you need is something flexible and possibly nearly flat to catch
the urine into. I use a takeaway container that is microwavable. Again, very
clean and scorched with boiling water. I have these items ready near the
litter box.
When I want a sample, I move the litter box  so that it is as much
approachable from all around as possible.
Once your cat approaches the box, and gets ready to pee, you have just
enough time to grab the 'catch tray' (e.g.. takeaway container). Wait till
your cat starts peeing. Put your 'catch tray' under its bum and...catch it!
once the cat starts the business, it won't stop till it's done.
Once you have it, transfer it straitaway into the sample bottle. Give it a
few minutes to cool, then put in the fridge if you have hours before seeing
the vet. A sample will hold in the fridge for about 24 hours.
*Additional hints: Since you have kittens, they may respond to training that
Xena and I gave each other: I used to praise her heaps for using the litter
tray. She in turn wanted to please me, and thought, that the best idea to
get me to know how well she has done, was to call me when she was ready to
make a 'deposit'. It often happens in the best part of a movie, and not
during a commercial break, but I am glad she calls me at all. Kittens learn
quickly, so praise them heaps, and they may use them same tactic to train
you.
** Hint number two: Cats usually use their box soon after a meal. Just lurk
around after their dinner and...follow them.
***Cats usually don't mind if you are present while they pee.
Good Luck!
Andr0 & >^^< :)

You're welcome!
Btw, Xena is getting better all the time; her crystals have decreased
considerably; I can see that her litter box activity has improved a lot, but
she will have to produce a couple more samples before taken of the hook; but
will remain on maintenance diet for quite a while - luckily, she loves it!)
Andr0 & >^^< :)