switching between WAPs

[C Thala]

I have two primary WAPs that I connect to on my FreeBSD desktop, my
rc.conf contains these entries:

   ifconfig_ipw0="ssid wap1 DHCP"
   ifconfig_ipw0="ssid wap2 DHCP"

The problem is that depending on which place I am at, I have to boot
up, have networking fail, edit the rc.conf file, comment out the WAP I
am not using and uncomment the WAP I am using and either restart netif
or reboot.

I have to do this everytime I go to the other wap.

That OS from the NorthWestern US seems to keep a list of WAPs and will
detect whenever you are in the vicinity of one and use the available
one. How can I get FreeBSD to do the same?

C