We do use Fast Etherchannel between a Catalyst 3524 and a catalyst 5000 with for links (400 Mbps).
Hoping it could be useful for you, here are the configs of the two switches.
The config of the Catalyst 3524 uses :
interface FastEthernet0/1
description FASTETHER1
port group 1 distribution destination
spanning-tree portfast
!
interface FastEthernet0/2
description FASTETHER2
port group 1 distribution destination
spanning-tree portfast
!
interface FastEthernet0/3
description FASTETHER3
port group 1 distribution destination
spanning-tree portfast
!
interface FastEthernet0/4
description FASTETHER4
port group 1 distribution destination
spanning-tree portfast
The config of the Catalyst 5000 includes
(the card must permit Fast Etherchannel, old cards don't permit):
set port channel 5/1-4 on