Based on my experience, it appears that you can - although that is not recommended since you will consume a lot of data. My L1020 seems to have partially downloaded the update before, but when I noticed that I switched to Wi-Fi for the remainder of the update. Others may confirm or debunk this for me.
P.S.
By the way, users are encouraged to post their queries in the respective forums. The Ask a Question forum is reserved for time-pressing matters and for guests who don't have an account yet.