In their Custom Keycap Designer, you can have only two legends per key and each legend has only one style. A style includes a font, weight, size, slant and justification.
However, you can let a legend span multiple lines and I think that also blank newlines and spaces to the left of a character are allowed.
For instance, I made my Swedish ISO #9 character as two legends: left-justified ")<newline>9" and right-justified "<newline>]".
WASD's engraving is a bit crude, so it might be the totally wrong choice for this. I would advise laser-etching.