If your comcast modem is actually a modem and router all in one device, what you would need to do is plug the comcast router into one of the ports on your 3750, preferably Gi1/1 for simplicity. Then plug your Airport Extreme Wifi Access Point into another port on the switch, probably Gi2/2 for simplicity. On your airport extreme you will want to disable DHCP and NAT. Run DHCP on the switch or let your comcast router do this, if you do it on the switch disable DHCP on the comcast router too.
Then create your SVIs on the switch (Vlan Interfaces). Each VLAN interface can be on it's own subnet so for example "Interface Vlan10" should be given an IP Address for your normal home network (on the same IP subnet as on your comcast router). Assign vlan10 to ports Gi1/1 and Gi1/2 (The comcast router and your wifi access point). Then assign vlan 10 to any other ports that are connected to home pc's. Then create another vlan interface, for example "Interface vlan20" with an IP address different than your home network. So like 10.0.0.0 255.255.0.0 or something. Then plug in your home lab to any of the other ports and assign those ports to vlan20.
Finally, if you want your home lab to have internet access, set the default route on the 3750 to the vlan interface of the home network SVI.
I think this is correct, you might have to mess with the config a little but this is the general idea.
