Cisco TAC does not support running autonomous IOS (aIOS) on the 3500 or 3600 Series Access Points. These access points are supported only when running in lightweight mode (Cisco Unified Wireless Network.)
The 12.4(25d)JA1 aIOS image for the 1260 series access point (ap3g1-k9w7) will load on a 3500 series AP, and may be used on an "as-is" basis. Cisco will provide no support for this use case, and will not warrant that future 1260 aIOS images will continue to load on 3500 series APs.
The 1260 series AP aIOS images will not load on a 3600 series AP, which requires an ap3g2 image. There are no aIOS images available for the 3600 series.