OS: Windows 7 Ultimate
Connection: Clearwire 4g wimax, USB modem pxu1900.

I noticed that TCP optimizer doesn't recognize my USB Wimax adapter as a network adapter, because it is not in the drop-down list of adapters. I've managed to change the MTU manually to 1500 via device settings, but I believe there may be further incompatibility.

TCP Analyzer states:

SpeedGuide.net TCP Analyzer Results
Tested on: 2012.06.09 16:15
IP address: 50.8.xx.xxx
Client OS/browser: Windows 7 (Firefox 13.0)

TCP options string: 020405b401010402
MSS: 1460
MTU: 1500
TCP Window: 64240 (multiple of MSS)
RWIN Scaling: 0 bits
Unscaled RWIN : 64240
Recommended RWINs: 64240, 128480, 256960, 513920, 1027840
BDP limit (200ms): 2570kbps (321KBytes/s)
BDP limit (500ms): 1028kbps (128KBytes/s)
MTU Discovery: ON
TTL: 121
Timestamps: OFF
IP ToS: 00000000 (0)

How can I change the RWIN to one of the higher recommended values?
I seem to have scaling enabled, yet Analyzer always reports zero scaling, with RWIN set to 64240.