What is the substitute for usepackage{cite} in beamer?

In my personal experience, these kinds of citations are quite useless in an actual conference/thesis presentation. However, you might be writing some lecture presentation where these could be more useful. In any case, here is a reminder on the recommandations regarding citations inside of a beamer presentation (see beamer user guide §5.1.2 p 34).

Bibliographies. You may also wish to present a bibliography at the end of your talk, so that people can see what kind of “further reading” is possible. When adding a bibliography to a presentation, keep the following in mind:

• It is a bad idea to present a long bibliography in a presentation. Present only very few references. (Naturally, this applies only to the talk itself, not to a possible handout.)
• If you present more references than fit on a single slide you can be almost sure that none of them will be remembered.
• Present references only if they are intended as “further reading.” Do not present a list of all things you used like in a paper.
• You should not present a long list of all your other great papers except if you are giving an application talk. 34
• Using the cite commands can be confusing since the audience has little chance of remembering the citations. If you cite the references, always cite them with full author name and year like “[Tantau, 2003]” instead of something like “[2,4]” or “[Tan01,NT02]”.
• If you want to be modest, you can abbreviate your name when citing yourself as in “[Nickelsen and T., 2003]” or “[Nickelsen and T, 2003]”. However, this can be confusing for the audience since it is often not immediately clear who exactly “T.” might be. We recommend using the full name.

Regardless of these recommandations, your question is very close to Citing a range of papers using numeric keys as in cite{a, b, c} -> [1-3]. Will Robertson's nice answer there provides three options to obtain the desired result.

As you pointed out, usepackage{cite} does not suffice here. However the other two options (with either biblatex or natbib) work fine with beamer. I recall them here, but these are pretty much copy pasted from Will Robertson's answer.

With biblatex

documentclass{beamer}
usepackage[style=numeric-comp,backend=bibtex]{biblatex}
bibliography{xampl}
begin{document}
hello cite{article-full,book-full,mastersthesis-full}
printbibliography
end{document}

With natbib

documentclass{beamer}
usepackage[numbers,sort&compress]{natbib}
begin{document}
hello citep{article-full,booklet-full,mastersthesis-full}
bibliographystyle{unsrtnat}
bibliography{xampl}
end{document}