Changing min/max ui values

My apologies if this is a silly question, but I have no experience editing shaders.

I want to change the range of possible values allowed in the UI, since when editing by hand in previous versions it was possible to get some really interesting effects when values fell outside the recommended range.

For example, a simple one is levels - reducing the range for black point and increasing it for white point.

Looking in the fx I see these lines:

uniform int BlackPoint <
ui_type = "drag";
ui_min = 0; ui_max = 255;
ui_tooltip = "The black point is the new black - literally. Everything darker than this will become completely black.";
> = 16;
uniform int WhitePoint <
ui_type = "drag";
ui_min = 0; ui_max = 255;
ui_tooltip = "The new white point. Everything brighter than this becomes completely white";
> = 235;

Can I just change the ui_min and ui_max values to whatever I want (e.g. ui_min = -100; ui_max = 300) or is there another setting I have to change as well? And will that method work for all shaders?

Additionally, if I want to distribute a preset that uses these modified ui values, would I be able to just distribute the profile as normal, or would the end users need to have this modified levels.fx (and any other fx files changed) for it to register? And if they do need the modified version, what would be the status of distributing it to paste and replace the original (since distributing shaders isn't allowed)?

Ctrl + Click on a widget to enter values beyond the default range. Yes, stored in a preset they will work regardless.
You can still edit the shader files (you found the right place) for your own convenience, but there is no need to distribute them.

Oh that's great you added in the option to do it via the UI - I'm really grateful for that, thank you. Good to know it'll all work for others just with the preset too. Thanks very much for the quick reply