How to mod year length?

[RoboticManiac]

Contrary to what I assume most players think, years fly by for me at a breakneck speed. I'm wondering how (Or if) I can mod year or day length.

[BlackSmokeDMax]

I wouldn't mind adding maybe 5 or 10 days per season. I like the new day length though.

[Mathenaut]

Having a longer day would be nice.