As I read that article I don't think it applies to the OP's statement. The article appears to be a possible fix for an out of control kernel_task that consumes large amounts of CPU time as opposed to the OP's statement that it is using a lot of memory. This is not really a problem that the article will fix. I'm not sure it even is a problem. Most users reporting information about the size of the kernel_task seem to have numbers around 1 GB, more or less, in Mountain Lion. Mine is just under 1 GB. I run mostly the same applications as the OP.
I think the OP's problem is he's running too many applications concurrently, and is too low on memory for the number of concurrent tasks. He may just need more RAM. My computer has 12 GBs of RAM. I have turned off the dynamic pager, yet I have more than enough free memory. However, this machine would choke if it only had 4 GBs of RAM.
Searching and searching everywhere, I've probably found the explanation for this problem:
The Intel HD 4000 graphic card consumes up to 768Mb from RAM. That's why kernel_task is using this amount of memory.
Hope this helps.
Use this at your own risk. It worked for me.
1- Click in the apple logo on the upleft corner, select "About This Mac".
2- Click in "More Info".
3- Click in "System Report".
4- Take note of "Model Identifier".
5- Create a new folder called "Recovery_Kernel_Task".
6- Select Macintosh HD/System/Library/Extensions/IOPlatformPluginFamily.kext
7- Click the mouse right button at that file and select "Show Package Contents"
8- Open the folder Contents/Resources.
9- Look for the Model Identifier in step 4.
10- Move the file to the folder you've created, if you need to restore the file.
11- Check the folder in step 8 has 49 files instead of 50 (original files).
12- Restart the computer and be happy!