Lot of people are going to tell you it can’t be done. If you play around with this tool - particularly the Transfer by College and the Transfer by Year tabs, you’ll find that a handful of people do transfer from CSU LA to UCs every year. (16 last year)
http://www.universityofcalifornia.edu/infocenter/admissions-source-school
The reason people go to CSU LA is to earn a BS/BA from there rather than transfer. Enter the process not expecting much support but, knowing it is possible but not as common as going from a CC - LA City had 174 UC transfer admits last year. Note required courses and GPA threshold are essentially the same for applicants from CSULA and LACC.
TAG is certainly a better worn path and may be worth considering if you know you are bent on a UC and don’t feel comfortable forging your own way. It is easy to find the classes you need and GPA threshold for the 6 campuses that use the program. Most CCs are a very different mix of student than a CSU - Some hell bent on Cal ASAP and others who attend part time and don’t have a plan at all. Just something to think about.
I will caution that earning a competitive GPA in a CS program (CC or CSU) is no picnic.