The trusty ol’ flanger from the ModFactor still has a lot of life in it. I’d start by setting Intensity & Depth to midpoint, all the secondary mod controls off, or minimum, then switch through the various Types and Shapes. Probably Sine or Triangle for the latter.
The new Instant Flanger algorithm is really great. You can target just the high frequencies. It is a bit more complicated to set up, though. I don’t have any Boss pedals, so I’m not familiar with their newer modes. Sounds to me like more feedback / regeneration in one, and a gated / panning effect in the other.
There are several flanger-based Programs up at PatchStorage that might give you a head start.
