You can accomplish this using a HotSwitch. Map the manual mod parameter to the HotSwitch and determine where you’d like the start/end points to be. You can then use the momentary or latching HotSwitch to jump back and forth between these values with the footswitch. You can also map the active/bypass state to the HotSwitch as well.
https://cdn.eventideaudio.com/manuals/h90/1.9.4/content/edit-modes/parameters.html#hotswitch
