How do I play WotLK with MoP?

[GnohVindi]

How do I play WotLK 3.3.5a with MoP 5.4.2?

[woloss]

You can't do something like this. You need to download 3.3.5a client and place to another directory. Only this way you can play LK and MoP

[Michiel1234]

you cannot play any old expansions trough a new client. Wotlk client 3.3.5a only works for Wotlk 3.3.5a and same for MoP client 5.4.0