you have to establish a peer to peer connection from your devices to the laptop doing the ICS.
Smartphones may not do peer to peer wireless, or you may not have the settings right to allow it if a laptop can't see it.
I'm not up to speed enough with Windows 8 to advise on setting up a peer to peer / adhoc wireless network. What you're trying to do is :-
3G modem in PC for internet connection
ICS shares internet connection using wireless on the PC
client PCs have ad-hoc or peer to peer wireless link to PC
if you can't get ad hoc connection between PCs you've fallen at the first fence.
--
Phil
MaxDSL - goes as fast as it can and doesn't read the line checker first.
MaxDSL diagnostics