If you have installed .Net and Powershell, this script will load a textfile into a Watchlist ala the original dbUpdate_watchlist.cmd but there is not the size limit problems people have been having with the cmd file.
This is code pulled from the other script I recently posted here, copy this into the %_ENVISION%\database\cmd directory. It is run just as the original dbUpdate_watchlist.cmd:
>./dbUpdate_Watchlist.ps1 <Wacthlist> <input file>
