How can I shoot a timelapse with a Canon Powershot camera?

I don’t think a timelapse is possible with that camera, given that it’s sort of a barebones point and shoot without many external interfaces. Getting a physical intervalometer would require having something that can repeatedly press the shutter button on the camera.

Most add-on intervalometers require a shutter release port on the camera, which the IXUS/ELPH cameras do not have. And they do not have intervalometer functions in their menus. While the 190 IS does have wi-fi capability that would let you connect to the Canon Camera Connect app, whose remote shooting functions can take the place of most shutter remotes, the app does not include an intervalometer function.

Typically in this situation, with most Canon Powershot cameras, the CHDK (Canon Hack Development Kit) would probably be the answer, but it looks like there is no build for the IXUS 180/ELPH 190 IS. And since this is a firmware hack, using a build for a different model/firmware version could brick your camera.

You may want to consider getting a different point and shoot camera, say, a Panasonic ZS or a higher-end Powershot, that has a time lapse function in its menus, if this is really important to you.