打开目录 Program Files\Common Files\Borland Shared\DBExpress，修改 dbxconnections.ini。

增加内容：

[FBConnection]
DriverName=Firebird
Database=database.fb
RoleName=RoleName
User_Name=SYSDBA
Password=masterkey
ServerCharSet=
SQLDialect=1
ErrorResourceFile=
LocaleCode=0000
BlobSize=-1
CommitRetain=True
WaitOnLocks=True
Interbase TransIsolation=ReadCommited
Trim Char=False

修改 dbxdrivers.ini：

[Installed Drivers]
DB2=1
Firebird=1    
Interbase=1
MySQL=1
Oracle=1
Informix=1
MSSQL=1

增加内容：

[Firebird]
GetDriverFunc=getSQLDriverINTERBASE
LibraryName=dbexpint.dll
VendorLib=fbclient.dll
Database=database.gdb
RoleName=RoleName
User_Name=SYSDBA
Password=masterkey
ServerCharSet=
SQLDialect=1
BlobSize=-1
CommitRetain=True
WaitOnLocks=True
ErrorResourceFile=
LocaleCode=0000
Interbase TransIsolation=ReadCommited
Trim Char=False

[Firebird TransIsolation]
ReadCommited=1
RepeatableRead=2

（出处：http://www.3asoft.com/forums/topic/11553.html）