How do I upload Cyanagenmod when the only things I have access to are Download mode and ClockworkMod recovery? I have a Samsung Galaxy Tab 7, the UK version. I managed to mess up in the beginning when trying to install CM and now have it in a state where I can either boot into Download mode or ClockworkMod Recovery.

The instructions say to use ADB to connect and upload the zip file, but this doesn't seem to work in either of the two modes I can boot into. I can no longer boot into stock Android to copy the file across there either.

How do I upload the CM zip file? Is there another step I'm missing?
In recovery mode, use this:

adb shell mount /sdcard
adb push {filename} /sdcard/{filename}


UPDATE #1: An alternative suggested by ce4: 


  Pull out the SD card, copy all needed files externally, and put it
  back in


UPDATE #2: It seems the user did not install CWM correctly. After fixing this, adb push now works as expected.