If you have a list of words in Excel, send it to email@example.com. We will import it for you and then add it to your account. (We're working on a public import tool you can use on your own, and will release it when it's ready).
We only need one column: "simplified" (or "traditional") which should contain your words:
Some words may be ambiguous. For example, 行 could mean háng or xíng. For this reason, you may want to add columns for pinyin or English (or both) to help us determine which word you mean. (Don't spend too much time on this -- most words match 1:1 with words that are in our dictionary. If you'd like, we can import first and then let you know which words we need clarification on before a secondary import.)
Heads up: If you plan to learn some imported words as new, and assume knowledge of others, you need to segregate your words into more than one list before sending it to us.