kernel 2.4.24 NO '/proc/net/ip_masquerade' whatever configuration

Hello,
Sorry for going on your nerves with this kind of newbie question, but I have
no ideas (any more) of how to solve this problem ... for now I have tried
many, many times to compile a kernel with MASQ support without success and
meanwhile I updated to 2.4.25-pre8 in the hope a newer kernel would bring
the solution.

<--- SNIP --->
#
# Networking options
#
CONFIG_PACKET=y
CONFIG_PACKET_MMAP=y

CONFIG_NETFILTER=y

CONFIG_UNIX=y
CONFIG_INET=y

CONFIG_SYN_COOKIES=y

#
# IP: Netfilter Configuration
#
CONFIG_IP_NF_CONNTRACK=y
CONFIG_IP_NF_FTP=m

CONFIG_IP_NF_IRC=m

CONFIG_IP_NF_IPTABLES=y

CONFIG_IP_NF_MATCH_MAC=m

CONFIG_IP_NF_MATCH_MARK=y
CONFIG_IP_NF_MATCH_MULTIPORT=y

CONFIG_IP_NF_MATCH_TCPMSS=m

CONFIG_IP_NF_MATCH_CONNTRACK=m
CONFIG_IP_NF_MATCH_UNCLEAN=m

CONFIG_IP_NF_FILTER=y
CONFIG_IP_NF_TARGET_REJECT=y

CONFIG_IP_NF_NAT=y
CONFIG_IP_NF_NAT_NEEDED=y
CONFIG_IP_NF_TARGET_MASQUERADE=y
CONFIG_IP_NF_TARGET_REDIRECT=m

CONFIG_IP_NF_NAT_IRC=m
CONFIG_IP_NF_NAT_FTP=m
CONFIG_IP_NF_MANGLE=y

CONFIG_IP_NF_TARGET_LOG=y

CONFIG_IP_NF_TARGET_TCPMSS=m
CONFIG_IP_NF_ARPTABLES=m
CONFIG_IP_NF_ARPFILTER=m
CONFIG_IP_NF_ARP_MANGLE=m

[for better readability I left out the outcommented rows]
<--- SNIP --->

'ls /proc/net' doesn't show ip_masquerade:

root@fire net # ls -l
total 0
-r--r--r-- 1 root root 0 Feb 4 14:50 arp
-r--r--r-- 1 root root 0 Feb 4 14:50 dev
-r--r--r-- 1 root root 0 Feb 4 14:50 dev_mcast
dr-xr-xr-x 2 root root 0 Feb 4 14:50 drivers
-r--r--r-- 1 root root 0 Feb 4 14:50 ip_conntrack
-r--r--r-- 1 root root 0 Feb 4 14:50 ip_tables_matches
-r--r--r-- 1 root root 0 Feb 4 14:50 ip_tables_names
-r--r--r-- 1 root root 0 Feb 4 14:50 ip_tables_targets
-r--r--r-- 1 root root 0 Feb 4 14:50 mcfilter
-r--r--r-- 1 root root 0 Feb 4 14:50 netlink
-r--r--r-- 1 root root 0 Feb 4 14:50 netstat
-r--r--r-- 1 root root 0 Feb 4 14:50 packet
-r--r--r-- 1 root root 0 Feb 4 14:50 raw
-r--r--r-- 1 root root 0 Feb 4 14:50 route
-r--r--r-- 1 root root 0 Feb 4 14:50 rt_cache
-r--r--r-- 1 root root 0 Feb 4 14:50 rt_cache_stat
-r--r--r-- 1 root root 0 Feb 4 14:50 snmp
-r--r--r-- 1 root root 0 Feb 4 14:50 sockstat
-r--r--r-- 1 root root 0 Feb 4 14:50 softnet_stat
-r--r--r-- 1 root root 0 Feb 4 14:50 tcp
-r--r--r-- 1 root root 0 Feb 4 14:50 udp
-r--r--r-- 1 root root 0 Feb 4 14:50 unix
-r--r--r-- 1 root root 0 Feb 4 14:50 wireless

And iptables doesn't seem to know Masquerading as well:

<--- SNIP --->
root@fire root # iptables --version
iptables v1.2.8
root@fire root # iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
iptables: Invalid argument
<--- SNIP --->

ANY hints will be greatly appreciated, since I am already on the edge of
getting heavily frustrated ...
BTW I am running Gentoo.

Thanks,
Mario