It wouldn't work if you simply substitute the term "ssget" in place of "entsel" -- the functions use different arguments [e.g. you can't spell out a prompt in (ssget), but it has many powerful options that (entsel) doesn't]. See the AutoLisp Reference for details on how to use it -- that will be the best elaboration. If you try it and it doesn't work, you can post what you tried, and someone will probably be able to tell you how to fix it.
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Kent Cooper
Kent Cooper, AIA