Then, in the process where you want to move it to an alpha, you just say:

             CNV TEXT <alpha field> = <numeric field>

The CNV TEXT field will honor the default display mask, and put the minus sign where you want. If you put currency symbols, commas, etc, they will also be formatted into the alpha field. The same thing applies if you use a date field as the source, APPX will format the date according to the date mask, so you don't get '20010517--------', you get '5/17/2001'.

APPX will use your default mask in other places as well, which may or may not be a good thing (inputs and outputs that use the numeric field will be affected). If you are concerned about that, you can create a new numeric field with the default mask you want, SET the original field into the new one, and then use CNV TEXT.