You can use cross-stitch patterns in a pinch but be aware that the proportions of a knit stitch, unlike a cross stitch, are not square. For alphabets it's not a biggie, but for other designs this is noticeable. Stockinette in sport or fingering yarn has a width::height ratio of 5::4 (it's wider than it is tall).
[click to enlarge.]
[some of the letters in action]
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