I think it's unlikely the pinouts on Meridian's Speakerlink cable are different to standard cat 5/6+ (as far as my knowledge goes neither is cat7 as this requires very different connectors?). This is based on experience when I used the flat cat5 SL cable between my switch/MC200/818 after I sold my 5200SLs. It worked perfectly.

I should add that I've heard significant differences between analogue cables over the years, very small differences between SPDIF, and Speakerlink (when feeding DSP from endpoint), but none at all in Ethernet (network) configuration. E.g., used as pure network cable I can't hear a difference between £200+ of Meridian SL cable and the (well constructed, good quality) Cat 6+ wires I now use in its place for this application (the SL wires are much too long and look messy, so they're in the cupboard!).

HC: 861v4/ID40/LPS, DSP5000, DSP5000VC, DSP3100, SW1600, HD621, Oppo BDP-105, Sony VPL-HW55ES
2-Channel: Oppo BDP-105, TEAC VRDS-7/Trichord Clock 3/PSU, 551, Quad 303, Harbeth Compact 7ES-3, Kimber cables, Russ Andrews mains and supports.
Previous Meridian: 5000C, 5200SL, 7200.2, 6000, 562V.2, 568.2mm, 800v4, 808.2i, 818v2/v3, 861v8, 502