Hi,
If you are using the newer version like...8.3 then you can customize it.
Here is the attached sample web auth file "Login1":
How to setup : http://www.cisco.com/c/en/us/td/docs/wireless/access_point/mob_exp/83/user_guide/b_ME_User_Guide_83/b_ME_User_Guide_83_chapter_0110.html
Regards
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