  By means of numerical experiments we explore the application of
interferometry to the detection and characterization of abundance spots in
chemically peculiar (CP) stars using the brightest star eps~Uma as a case
study. We find that the best spectral regions to search for spots and stellar
rotation signatures are in the visual domain. The spots can clearly be detected
already at a first visibility lobe and their signatures can be uniquely
disentangled from that of rotation. The spots and rotation signatures can also
be detected in NIR at low spectral resolution but baselines longer than 180~m
are needed for all potential CP candidates. According to our simulations, an
instrument like VEGA (or its successor e.g., FRIEND) should be able to detect,
in the visual, the effect of spots and spots+rotation, provided that the
instrument is able to measure $V^2\approx10^{-3}$, and/or closure phase. In
infrared, an instrument like AMBER but with longer baselines than the ones
available so far would be able to measure rotation and spots. Our study
provides necessary details about strategies of spot detection and the
requirements for modern and planned interferometric facilities essential for CP
star research.
