It should work - provided that your CF disk to IDE adaptor does follow the ATA-4 standards fully, and can operate at UDMA mode 4 (ATA-66) and MDMA mode 0.
I think that OPL allows you to select the data transfer type and mode, but HDLoader will run the disk at it's "normal" (maximum for the PS2) speed - UDMA mode 4.
Unmodified SCPH-77006 with SM 3.6
SCPH-39006 with M-chip modchip, SCPH-10281 NA and refurb Seagate 80GB HDD
SCPH-10000 v1.00 with SCPH-10190 PCMCIA NA and SCPH-20400 HDD unit