ah, ok. We're heavy users of the ACS, and find that they generally work ok (but that's neither here nor there)
As a starter, I'd recommend investigating the Wireless Domain Services (WDS) capabilities, this allows roaming between AP's without re-authentication, so you setup a master AP that controls this. The configuration itself is pretty simple, when I did ours I didn't have a good understanding of AP CLI, so used the web interface (which was really easy), I found a good guide on the cisco website for this - I'll try and dig it out...
The 802.1x part can be handled by RADIUS, so assuming that IAS supports this (would have thought so) then it's all standards based with EAP, for which you can use Certs or not - I've never used certs for this as we use LEAP which backs off to NT LDAP.
As an aside, how are you finding the IAS boxes? I'm looking to use 802.1x to map users to VLAN's...
/edit - Doc from Cisco - gives a good overview + config, some applies to ACS, but sure you could adapt to fit:
http://www.cisco.com/en/US/products...s_configuration_example09186a00801c951f.shtml