Tier 2 general dependent, switch from tier 1 post study work

[icic]

I am currently working in UK under Tier 2 general, my wife has been in uk for three years and she is currently using Tier 1 post study work. Her current PSW visa is about to expire and she wants to switch to Tier 2 general dependent. Can she apply the tier 2 dependent in the uk or she has to leave uk and apply entry clearance? This is her first time to apply visa as my dependent. I checked the home office web, for tier 2 it is not clear to me. Thanks.
But for tier 1 general, it is clearly state that the first time applying for the dependent have to leave uk and apply entry clearance.

[vinny]

An applicant who is applying for leave to remain, must have, or have last been granted, leave:

(i) as the Partner of a Relevant Points Based System Migrant,

Entry to the UK

(a) Subject to paragraph (b), all migrants wishing to enter as the Partner of a relevant Points Based System Migrant must have a valid entry clearance for entry under this route. If they do not have a valid entry clearance, entry will be refused.