RG Live WotLK 3.3.5a

Ist blizzlike :)

if you enter from the front entrance, you will find the whole thing much more simple and linear. done it 2 times this week, with a warr and a hunter. you still need the kara or blacksmithing key, or a rogue to pick the lock to enter. starting from the front door will allow you to do attumen as first boss, and the way will be much more easier. another tip i can give u is to search on wowwiki/wowpedia which provides a detailed map of the raid with the location of each boss.
hope i've been helpful =)

http://www.mmo-champion.com/threads/860201-Karazhan-side-door

http://www.wowhead.com/forums&topic=116181/guide-to-lockpicking#p1384809

So I want to go and solo Karazhan... I do the quest chain, get the key, get a friend to sit in a raid group with me while I do it... I down all the first couple of bosses, easily... With no problem at all... Then I get to this door that says "Locked"... Friend tells me its ok, I can just use the side entrance... So I go over there and once again right inside the instance is a door the says "Locked"...

So is that it then? I can't solo Karazhan unless I have a rogue or an engineer with me? Or is there another way in?

http://www.gamefaqs.com/boards/534914-world-of-warcraft/57585640

Karazhan Karazhan Door 350 70 Can also be opened with The Master's Key

http://wowwiki.wikia.com/wiki/Lockpicking
Also, the doors to Karazhan and Violet Hold and pickable.