Latex commands in math mode

[Friedrich Hagedorn]

Hello,

how can I add real latex commands in the math mode? I use Lyx 1.5.1 for
Linux.

E.g. I want to insert a

  \intertext{blah blah}

before a equation, or add

 \\[2em]

after a euqation. I tried Ctrl-l and '\' but this didnt work.

Thanks,

  Friedrich