yes you can- the command is called chmod, and it changes file permissions.
I won't go into detail about how it works- just google 'chmod' and you can find lots of information, but for your case, you probably only need to know this:
sudo chmod -R 777 /Users/<you>
Just type that into terminal, provide your password, and the permissions on every file in /Users/<you> should be changed to 'free for all'
In case you want to know,
sudo means run with administrative privileges
-R means apply command recursively to every subdirectory and file in the directory
777 means rwxrwxrwx means that anybody has the permissions to read, write and execute the files
/Users/<you> can be changed to anything you want, in fact if you're running off live cd it might be /Volumes/MacintoshHD/Users/<you>, i'm not sure how it works, you might want to check.
If you're daring enough you could just apply it to / which means everything in the filesystem although that might mess up some system files, so I wouldn't recommend it.
Hope that helped.