It is not working, here is my config.
[admin@MikroTik] > ip proxy expo
# mar/19/2014 07:46:18 by RouterOS [code]6.10
# software id = F6R9-UR4F
#
/ip proxy
set enabled=yes port=3128
/ip proxy access
add action=deny dst-port=80 redirect-to=192.168.1.75 src-address=\
192.168.1.0/24
[/code]
[admin@MikroTik] > ip pr acc ex
# mar/19/2014 07:48:53 by RouterOS 6.10
# software id = F6R9-UR4F
#
/ip proxy access
add action=deny dst-port=80 redirect-to=192.168.1.75 src-address=\
192.168.1.0/24
/ip firewall nat
add action=masquerade chain=srcnat out-bridge-port=ether2 src-address=\
192.168.1.0/24
add action=redirect chain=dstnat dst-port=80 protocol=tcp src-address=\
192.168.1.0/24 to-ports=3128
[admin@MikroTik] > int bridge expo
# mar/19/2014 08:00:03 by RouterOS 6.10
# software id = F6R9-UR4F
#
/interface bridge
add l2mtu=1598 name=bridge1
/interface bridge port
add bridge=bridge1 interface=wlan1
add bridge=bridge1 interface=ether2
/ip address
add address=192.168.1.251/24 interface=bridge1 network=\
192.168.1.0