How do you customize your own Halo 3 map to look like a race course?

[Sam Wikwiki]

I was watching a Halo 3 video and saw people riding mongeese and warthogs on what looked like - and was suppose to be - a race track.
yes but i saw them picking up the whole sandtrap course and complety rebuild it!

 

[Eric]

I don't think so but i always call mongoose a mongeese and it sound pretty funny