If you're after low-res, get the Default Lemming Sprites pack here:
http://www.neolemmix.com/old/neoflexi.htmlIf you're after high-res, use the tool I posted a while back to extract them from WinLemm graphics. (You could technically get them from Lemmini / SuperLemmini's extractions, but those come with a clause in the licence agreement that prohibits redistribution of anything they extract - while I myself am not going to enforce that, and it's unlikely the creators will either, the creators theoretically
could. By comparison, my WinLemm extractor does not come with any such restriction.) Alternatively, if you only need one or two frames, you could simply take screenshots.
EDIT: Not sure where (or even if, to be honest) I posted that tool, so here's a re-upload. Should be simple enough to work; let me know if you have any difficulties. I don't actively support it so can't promise fixes to any bugs if they occur, but I'm happy to help with how to work it.