Hi,
My vet had me start off with once a day dosing for Lantus. He said that although mosts cats do need it twice a day, he didn't want to miss out on the possibility that Quincy was one of the rare cats who could do well with Lantus only once a day. If you look at Quincy's spreadsheet (in my signature file) you can see that I tried him on once a day for about a month. Like you, I was really concerned about my ability to give doses 2x a day, and most people on this board were very insistent that that was what I needed to do. I gave it a try, though, and did blood sugar tests throughout the day. It became pretty obvious, though, that once a day wasn't going to cut it, so I went to twice a day and that has made a big difference. In fact, Quincy is doing very well and now is on a dose of only 0.10 twice a day. I am glad I switched him to twice a day even though it's been hard at times because I think it did a lot to increase his chances for remission.
If you're really focused on dosing once a day, you could try it for a couple of weeks and test your cat's blood sugar every few hours (that's called plotting a "curve"). That would enable you to see how low he/she goes, and at what point in the cycle (many cats reach their lowest point about 6 hours after the shot), and then when he/she starts rising. If your cat reaches his/her lowest point around 10 or 12 hours and very slowly rises, then maybe you can get away with once a day. But again, that's very, very unusual, and you could be reducing your cat's chances of not needing insulin the rest of his/her life if you spend too much time trying to make one dose work. Increasing the amount of insulin given once a day won't help either - it just may make your cat go too low early and then jump back up later.
I hope this helps, and that you find a system that works for you. There is a ton to learn in the beginning - it's a very steep learning curve - but you do get the hang of things.