Prerequisites:

-You need to have a any stock /custom rooted rom with 2ndinit(bootmenu) installed.
Instuction for how to do this are given all over the forum, please search.

-Download cm7 and copy the zip file into the sd card : http://download.cyanogenmod.com/?typ...ce=umts_jordan

After that you will need the following things:

-install walter's defy+ rom:http://forum.xda-developers.com/show....php?t=1285007
Instruction are given in that thread as well.

-After installing the defy+ rom, reboot go to recovery > custom recovery > wipe data/cache, then goto advanced> wipe dalvik cache

-go back and select install zip from sd card> select the cm7 zip in sdcard

-After installing wipe cache partition and reboot