Working with Linux means from time to time to handle with text- or configuration 
files at runtime so there is no way to manipulate a component at design time.

The normal way for Delphi and Kylix is just to check a dbExpress configuration 
file, put a TSQLConnection on a form then double-click the TSQLConnection to 
display the Connection Editor (property editor) and set parameter values (database 
path, connection name etc.) to indicate the settings. 

But in the following example, all goes by runtime (path and login) with dbExpress 
we don't need an alias or the BDE either to open a dataset. 
Password could be encrypted in a follow up function or driven by user input. 

1   
2   procedure TVCLScanner.PostUser(const Email, FirstName, LastName: WideString); 
3   var 
4     Connection : TSQLConnection; 
5     DataSet    : TSQLDataSet; 
6   begin 
7     Connection:= TSQLConnection.Create(nil); 
8     with Connection do begin 
9       ConnectionName:= 'VCLScanner'; 
10      DriverName:= 'INTERBASE'; 
11      LibraryName:= 'dbexpint.dll'; 
12      VendorLib:= 'GDS32.DLL'; 
13      GetDriverFunc:= 'getSQLDriverINTERBASE'; 
14      Params.Add('User_Name=SYSDBA'); 
15      Params.Add('Password=masterkey'); 
16      Params.Add('Database=milo2:D:\frank\webservices\umlbank.gdb'); 
17      LoginPrompt:= False; 
18      Open; 
19    end; 
20    DataSet:= TSQLDataSet.Create(nil); 
21    with DataSet do begin 
22      SQLConnection:= Connection; 
23      CommandText:= Format('INSERT INTO t_runmax VALUES("%s","%s","%s")', 
24                               [Email,FirstN,LastN]); 
25      try 
26        ExecSQL; 
27      except 
28      end; 
29    end; 
30    Connection.Close; 
31    DataSet.Free; 
32    Connection.Free; 
33  end; 
34