FreeBSD 9 and gmirror /geom raid

[Davide D'Amico]

Hi, I have a server DELL R210 with two sata drives:
ada0 at ahcich0 bus 0 scbus0 target 0 lun 0
ada0: <SAMSUNG HE253GJ 1AJ30001> ATA-8 SATA 2.x device
ada0: 300.000MB/s transfers (SATA 2.x, UDMA6, PIO 8192bytes)
ada0: Command Queueing enabled
ada0: 238418MB (488281250 512 byte sectors: 16H 63S/T 16383C)
ada0: Previously was known as ad4
ada1 at ahcich1 bus 0 scbus1 target 0 lun 0
ada1: <SAMSUNG HE253GJ 1AJ30001> ATA-8 SATA 2.x device
ada1: 300.000MB/s transfers (SATA 2.x, UDMA6, PIO 8192bytes)
ada1: Command Queueing enabled
ada1: 238418MB (488281250 512 byte sectors: 16H 63S/T 16383C)
ada1: Previously was known as ad6

Previously (8.x) - when I didn't use a hw raid - I used to install freebsd  
in a drive (i.e. ad4), boot from it and then:

# sysctl kern.geom.debugflags=16
# gmirror label -v -b round-robin data ad4
# gmirror insert data ad6
// Modification to /etc/fstab
// reboot

How could accomplish to the same task with 9.0-RELEASE?

Thanks,

-- 
d.