Problem installing FreeBSD 6.0-RELEASE on HighPoint RocketRAID 1520

[Ilja Alaoja]

I've aquired a HighPoint RocketRAID 1520 SATA controller card, since it's
supposed to be very well supported under FreeBSD.
Unfortunately i can't seem to install FreeBSD 6.0-RELEASE. As a matter of
fact, the installation CD fails to boot.
My two disks are Seagate Barracuda 120 GB, and my motherboard is an Asus
A7N8X Deluxe (nForce2).
Verbose boot gives me this output, just before everything hangs.

ata0-master: pio=PIO4 wdma=wdma2 udma=UDMA133 cable=40 wire
ad4: setting PIO4 on HighPoint chip
ad4: 114473MB <Seagate ST3120026AS 3.05> at ata2-master UDMA133
ad4: 234441648 sectors [232581C/16H/635] 16 sectors/interrupt 1 depth queue
ad4: HighPoint (v3) check1 failed
ad4: HighPoint (v2) check1 failed
ad4: Adaptec check1 failed
ad4: LSI (v3) check1 failed
ad4: LSI (v2) check1 failed
ad4: FreeBSD check1 failed
ata1-master: pio=PIO4 wdma=wdma2 udma=UDMA133 cable=40 wire
ad6: setting PIO4 on HighPoint chip
ad6: 114473MB <Seagate ST3120026AS 3.05> at ata2-master UDMA133
ad6: 234441648 sectors [232581C/16H/635] 16 sectors/interrupt 1 depth queue
ad6: HighPoint (v3) check1 failed
ad6: HighPoint (v2) check1 failed
ad6: Adaptec check1 failed
ad6: LSI (v3) check1 failed
ad6: LSI (v2) check1 failed
ad6: FreeBSD check1 failed
GEOM: new disk ad4
GEOM: new disk ad6

Hopefully this is enough information to diagnose my problem. I would very
much appreciate any help I can get.

/Ilja Alaoja