you never had to do that. all you needed to do was edit the /etc/rc.d/rc.inet1.config
then when Slackware scripts do the rest. udev will re-write the rules.d every nic has a different mac unless
you flash new ones.
open a console as root type pkgtool select run scripts choose configure net.
or as root type netconfig.
rules have nothing to do with good connection it creates the device as the module is load then sets the permission per hal
location of mac
eth0 is default you change it only if you have two nic.
as root type
then you type ifconfig you will see something like this
eth0 Link encap:Ethernet HWaddr 00:24:8c:3e:db:74 <-------mac
inet addr:192.168.11.2 Bcast:192.168.11.255 Mask:255.255.255.0
inet6 addr: fe80::224:8cff:fe3e:db74/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:331716 errors:0 dropped:0 overruns:0 frame:0
TX packets:309260 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:324031872 (309.0 MiB) TX bytes:48022317 (45.7 MiB)
Interrupt:27 Base address:0x4000
if not you will have to type dmesg and look for your device and mac as they are being loaded into the kernel