Boot in CWM Recovery when CM7 runs on SD Card?

[XRAY]

How do I get there? I wanted to update my ROM by the Rom Manager ... he had to restart to get the work done in CWM Recovery...then I saw Linux command lines, but suddenly the device went off. When I start it again nothing was done to my CM7! I think its a problem because I'm running CM7 from SD Card. Is it possible for example, that CWM Recovery installs itself on the internal memory...and when the device is restarted, there are no CWM -Boot-Files on the SD Card?! So simply, how do I get ROM-Updates installed when I use CM7 from SD Card?! ;-) thx for your help