H1B/L1 and AOS Pending are two parallel and separate status'es. Only one of them is active. If you had not updated I-9 with EAD or not entered the country using AP, you are in H1B / L1 status. So you will follow the same steps assuming that you are in one status only. For H1B transfer follow whatever procedure that has been done before. If you want to complicate things, you can have multiple H1Bs at the same time.
The 180 days is concerning only the I485 and subsequent use of AC21 job portability. To avail that benefit you need to stay with the employer for 180 days from the notice day. After that period you can port without starting another PERM/I-140. You become a "free agent" after that 180 day period. That's why it is important to stay with your employer for 180 days.
Now if you do H1B transfer within the 180 days, then you violate your 180 day clock on the I485. So you may have to redo PERM and I-140 all over again.