How to get out of broken home screen replacement?
Assuming you have ADB access to your test device, you can issue the following command:

adb shell pm uninstall PACKAGE 

Where "PACKAGE" is the package name of your launcher app (you should know this since you're creating the app in the first place.)

[Edit]
As requested, re-posting my comment as the answer:
Every site for ZTE Blade has instructions for accessing the Fastboot mode via Volume Up + Power button combination. Eg: http://wiki.cyanogenmod.com/index.php?title=ZTE_Blade:_Full_Update_Guide Give that a shot and see if you can access the phone via fastboot.exe (should be in the [Android SDK]/tools/ directory.) At that point you can flash a different recovery image (Clockworkmod, Amon-Ra) that will allow access to /data/app to delete your program.