If this is a non-csh shell, the following should work. Lets assume your mysql library is in /usr/mysql/lib :

### Check current value (possibly SHLIB_PATH)
prompt > echo $LD_LIBRARY_PATH
/usr/local/lib:/usr/lib

### Add new path
prompt > LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/mysql/lib
prompt > export LD_LIBRARY_PATH

### Test it out
prompt > ./your_test_program.pl
  Driver: ExampleP
  Data Source is dbi:ExampleP:dir=.
  Driver: Proxy
  Driver: mysql
prompt >

### lather, rince, repeat
[download]

But, using make install was not meant to fix make test, but to ignore the errors. That is why i prefer not to do it that way. You said a program which worked elsewhere fails ... i would suggest writting a short bit of code to login to a mysql server, and do a select * ... if that works, the Driver is loading (which is what failed in make test), and the problem is either the version, or something else all together.