No need for any special access commands for this.
The command that you want is "show ap debug client-table ap-name <NAME>". This will show you RX SNR and rate and other goodies from the remote mesh nodes.
In the mesh context, "client" means another mesh node as opposed to a WiFi user station.
Here's a sample output:
#show ap debug client-table ap-name "Portal_Container"
Client Table
------------
MAC ESSID BSSID Assoc_State HT_State AID PS_State UAPSD Tx_Pkts Rx_Pkts PS_Qlen Tx_Retries Tx_Rate Rx_Rate Last_ACK_SNR Last_Rx_SNR TX_Chains Tx_Timestamp Rx_Timestamp
--- ----- ----- ----------- -------- --- -------- ----- ------- ------- ------- ---------- ------- ------- ------------ ----------- --------- ------------ ------------
00:24:6c:5a:08:29 Doha-Port 00:24:6c:5a:1e:78 Associated SI 0x1 Awake (0,0,0,0,N/A,0) 1134 1267 0 64 104 78 26 27 2[0x3] Mon Jun 4 18:14:50 2012 Mon Jun 4 18:14:50 2012
00:17:23:15:44:de Milahaport 00:24:6c:5a:1e:71 Associated None 0x1 Power-save (0,0,0,0,N/A,0) 49 125 0 2 11 18 31 32 2[0x3] Mon Jun 4 18:14:45 2012 Mon Jun 4 18:14:45 2012
#
You can repeat this for the AP on the other side of the link as well and get bidirectional SNR thay way.
If you want to filter on a specific node, just pipe the output to the INCLUDE command.
Full access is only available to Aruba support engineers in the TAC for specialized problem situations. Most Aruba engineers do not have access to this either.