It is fairly easy task however it has to be done in following way to avoid problems,e.g. for port ge.2.2 it should be like below:
set port negotiation ge.2.2 disable
this is mandatory, without that command there can be a lot of issues even though you set the next 2 command below. So please remember about it,as autonegotiations still will work together with fixed settings.
set port speed ge.2.2 100
type this command first before duplex settings
set port duplex ge.2.2 full
dzbanek 2012-10-19