I wonder how to do costum leader icons??
Like here
http://www.speedrun.com/dk64#Any%

I made a special exception for the DK64 community, because they had them on their old leaderboard and I didn't want them to feel like they'd be losing anything by moving here.

They're hardcoded.

O OK

You could add this for every user.

Would be awesome.

You just have to ask Pac to implement these special icons.

Gyoo: Lighnat0r released an update that everyone can do it now iirc

from changelog
Added: Ranking icons for 1st down to 4th place can now be customized in game themes.

ffzAWOOO

Yup, you can simply add them on the Add theme/Edit theme page of a game now.