It's possible, but Construct's spritesheeting algorithm is non-deterministic so you don't know ahead of time which images are on the spritesheet. However you can simply set the texture and draw it via its texture co-ordinates for a different image; if it happens to be on the same texture Construct will batch it in to the same draw, otherwise it will switch texture.
Still it's a weird question and asking the user to enter UVs is definitely not the type of thing you should be doing, especially since spritesheets can be completely rearranged at the drop of a hat, so any user-inputted UVs will quickly become invalid. As ever, it's best to explain what your overall goal is, rather than the specific details of a particular approach that might not be the right one.