You can also use the maxdiypower PS2 700XX serials SATA HDL installation kit for external connected SATA HD.
It use the ide port of the v12/v13 and is simply a ide/sata adapter.
I have tested it and it works very well with HDLoader (0.8b+ with v9 and v12/13 Patch).
I own self 2x PS2 Slim with Matrix Infinity and HD Combo and 2x PS2 Slim with Matrix Infinity and the SATA HDL installation kit (all soldered by Gametop.de).
- PS2 v3 DMS4 Pro ToxicOS 0.41 + Sony BBA 3.5 750 GB S-ATA HD
- PS2 v10 Ripper 3.41 + Sony BBA 3.5 1 TB S-ATA HD
- PS2 Slim MI 1.93 + HD-Combo black 120 GB IDE HD + 9,2' 16:9 PAL/NTSC LCD
- PS2 Slim MI 1.93 + HD-Combo white 750 GB IDE HD
- PS2 Slim MI 1.93 + SATA HDL Kit 1 TB SATA HD