Why does Mint 11 only have tesseract 2.1?
 

I want 3.0, is this achievable?

"Why" is a good question.
No Debian, Ubuntu, Mint version has Tesseact 3.

But it's easy to build Tesseract for Mint 11 :
sudo apt-get install zlib1g-dev libtiff4-dev libpng12-dev libjpeg62-dev

cd tesseract-3.0.0/ && ./configure && make && sudo make install

Will provide :
/usr/local/bin cntraining combine_tessdata mftraining tesseract unicharset_extractor wordlist2dawg

May be some more hints here http://ubuntuforums.org/showthread.php?t=1647350

.

I could only follow the guide until in a trainy data
Output:

Linux Mint 11 :
I have /usr/local/share/tessdata/ : configs/ : tessconfigs/


This source, tesseract-3.00.tar.gz was used :
http://tesseract-ocr.googlecode.com/...ct-3.00.tar.gz