You can watch my film (sorry, its in Halo, not youtube) to see approximately where to land. It is basically jumping off of a slant with forward momentum, giving you even more momentum. Try landing on the line where the fence box & double box meet.
I believe the second one is harder, but thanks still = ). And by building a jumping map (and testing it out to ensure each obstacle is possible, yet hard), you greatly improve your jumping. Btw, I think you may have necro-posted, although I don't know if that is still an offence.