I dont know if there is or whatnot because this is the way I do it:
Open up valve.rc in notepad and then you'll see this:
// load the base configuration
//exec default.cfg
// Setup custom controller
exec joystick.cfg
// run a user script file if present
exec autoexec.cfg
//
// stuff command line statements
//
stuffcmds
// display the startup level
startupmenu
Put a // infront of startupmenu to comment it out, and there you go. However I think I read this at tweakguide but cant really remember so do this at your own risk, personally I am doing it and still am, but if in the future valve decide that its illegal haxing then I am not responsible Im sure it wont though.