Hmm, it's possible, but I don't use GDM/KDM so this might not be 100% accurate, but should work *in theory*

I'll use GDM and ScrotWM as examples, Acid_RuleZz

first, confirm that you have the scrotwm.desktop (or just Scrotwm) entry in your usr/share/xsessions. If so, open it, and save it's contents to somewhere else (in case what I tell you here doesn't work and you need to revert)

Now replace its contents with this (you'll need root permissions, obviously):


You see the "/root/scrotwm.sh" script there? .... We're going to create that file now.

Go to your /root and create a file/document called scrotwm.sh and give it permission to run as an executable (either via teh Properties tab in your file manager or chmod in terminal)

Then, inside scrotwm.sh, add your startup apps like this example:


Replace those entries with whatever you use on your setup.
Please note that nm-applet might not work (since ScrotWM doesn't have a systray for you to run applets), but you can still try it. If not, you'll have to replace that line with the actual network manager command (which I do not know since I don't use network manager). the "feh" line is for your wallpaper, which means you should have feh installed  (it's in your repos).
Important: make sure you refer back to your regular Gnome sessions for all teh stuff you want started and the exact lines they need, since here I'm just assuming the commands for you... I don't use gnome). I added the setxkbmap line to default to a US keyboard and the synclient line for your touchpad tap-to-click function, remove em if you don't need.

Let me know if it works.

Your main problem will be the network manager. I'm sorry that I can't help further with that. I don't really know it's syntax, and I prefer wicd-curses myself (mainly cos wicd launches during the boot process, so I don't need to add it to any of my session startups and can control it via terminal)

Hope this helps,

Cheers.

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Added on December 19, 2010, 5:30 pm

@1faris
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