Hi there,
Our 1 year old boy has been using the (grown-up) toilet every morning since he was 6 months old. I sit on the back of the toilet seat and hold him on the toilet between my legs. I use "cueing" words and sounds to let him know that it is time to go. Ours are poo-poo and pee-pee and I also make a "Psssss" sound. He's a very active child so I always have toys next to me to keep him occupied otherwise he gets squirmy. Using this technique he happily poops on the toilet every morning and occasionally he pees also. You will probably need someone with you to hold the urine cup and be ready to act fast. Also, you could use a little potty. We used a potty for a while and I just placed it on the counter top in the kitchen and held him up on it. This seemed to work just as well, and would be more convenient for you to make sure you catch the pee.
We read about this approach in a book called "Diaper Free" and it is used around the world in places where people have always done this (since before diapers were invented). We are not diaper free, but it's nice not to have to change many poopy diapers (he mostly only pees the rest of the day)and I figure we have a leg-up (so to speak) on potty training...
'hope this is helpful, and maybe it might be useful for more than just the one urine collection!! Just a final note that we never keep him on the potty or the toilet if he doesn't want to do it at that time. Toys are helpful to convince him to sit still for a while, but they don't work every time. If he really want off, we stop and try again later. I don't want him to have any negative associations with toileting, so we are really careful about this.
Best,
J. (mom to Khalil, 12 months)