Por aqui fiz o código abaixo (no arquivo DPR), que atendeu bem as minhas necessidades:
var sModo : string; begin GetParamByKey('modo',sModo,'desktop'); if (AnsiLowerCase(sModo) = 'desktop') then begin Forms.Application.Initialize; Forms.Application.MainFormOnTaskbar := True; Forms.Application.Title := 'G!Guadian Master'; Forms.Application.CreateForm(TfModoDesktop, fModoDesktop); Forms.Application.Run; end else begin if not SvcMgr.Application.DelayInitialize or SvcMgr.Application.Installing then SvcMgr.Application.Initialize; SvcMgr.Application.CreateForm(TGGuadianMaster, GGuadianMaster); SvcMgr.Application.Run; end; end.