The general workaround to force modules into a PerlApp (and I guess PerlSvc) application is to do it manually somewhere in your code. So just put

#Foce load for PerlApp's sake
use DBD::ODBC;
[download]

somewhere. DBD::ODBC might use other "implicit" modules as well.

/J

Update: Misread "-a switch to my build and added the DBD::ODBC .dll" to mean that you used -a to add the .dll file. I guess the -a should do it, so if my suggestion works (it shouldn't), please let me know ;)