Thank you GonzoJohn for your article.
After reading through your article, it allows me to find out what was going on when the cardmgr scans the 2 pcmcia sockets. Surprisingly, contrary to what the DELL and RedHat support told me, cardmgr actually recognizes the cards (including the modem) and executes the drivers for it.
However, I notice that during the installation process, it did not actually bring up the host and ip address screen for you to enter the relevant information and so after the 1st boot, eth0 was inactive.
I went back to the log and found the following lines:
cardmgr: executing: './network start eth0'
cardmgr: executing: + usage: ifup <device name>
cardmgr: start cmd exited with status 1
and so I believe something was wrong. Since I don't know what 'status 1' means, I just went into X-Windows and use netcfg (if it doesn't work, use netconfig) to set the ip address and everything and it works perfectly! So, the installation was very straightforward but the main thing is you just have to be persistent.
Just for your information, I am running RedHat 6.2 on:
DELL Latitude CP233ST
3Com 3C575-TX CardBus
One thing though: there is a bit of a fiddling in configuring the monitor of the laptop. I cannot use the LCD 800x600 (unlike other DELL laptop models). You have to choose DELL super VGA (or other brand of VGA I reckon) and configure it manually - choose 2mb as the video memory and no clockset or something - the last thing is to choose 8-bit 800x600, others won't work.