Glueing is safe enough, but it's questionable how much it works. It won't give you rose ears if the dog doesn't naturally have them, it can help encourage a naturally rose ear that might be experiencing a wayward period. It's usually used to help a pup through the awkward period when they are teething and the ears go haywire. How successful it is is debatable, as the ears might have settled down fine eventually anyway.
If the pup in your avatar is the one you are thinking of, his ears look fine, and I'd probably just leave them be.
edited to say that I went and looked at your Dogster page, and there's no way that pup's ears will rose, so I wouldn't bother trying.