Taken from XDA, original link here. If this doesnt make sense to you just move along 
Hello All,
I have gotten infrastructure mode working on my EVO. I compiled support for the SIOCSIWPRIV AP_PROFILE_SET system call into iwconfig and lo and behold:
After unloading and reloading the _ap.bin firmware using insmod while wifi-tether is running I issue the following command:
Command: # ./ultraiwconfig eth0 mode master
Response in kernel log:
Code:
<4>[19452.040679] penguin, get AP_PROFILE_SET
<4>[19452.041076] wl_iw: set ap profile:
<4>[19452.041442] ssid = AndrewsAndroidAP
<4>[19452.042144] security = wpa-psk
<4>[19452.042510] key = 1234567890
<4>[19452.042877] channel = 0
<4>[19452.043243] max scb = 2
<4>[19454.110931] Set auto channel = 1
<4>[19454.112182] wl_iw_setap: do passhash...
<4>[19454.210723] [00]: aa2f2f2c
<4>[19454.210845] [01]: f4081ab1
<4>[19454.211059] [02]: ccc1d613
<4>[19454.211181] [03]: 887fd525
<4>[19454.211273] [04]: b51d0c01
<4>[19454.211395] [05]: 781b89b1
<4>[19454.211608] [06]: b5de9c57
<4>[19454.211730] [07]: 2f8812e2
<4>[19454.211853] wl_iw_setap: passphase = 2c2f2faab11a08f413d6c1cc25d57f88010c1db5b1891b78579cdeb5e212882f
<4>[19454.222106] ap setup done
<4>[19454.224487] send AP_UP
And proceed to assign IP information and bring the interface up.
The interface then appears on my Windows 7 laptop in infrastructure mode fully supporting wpa.
I will be working with Harald in the coming days to integrate this functionality into android-wifi-tether!