The Custom Functions utility lets you create custom functions that can be reused anywhere in the database file in which they are created. (more at: http://www.filemaker.com/help/13/fmp/en/html/fmpa_custom.23.4.html).
In lieu of self, you can pass the name of the field via a script parameter. You can pass the contents of the field by defining the script paramter as Table :: field. You can pass the name of the field using GetFieldName ( table :: field).
I use the latter option quite often in my database in order to reuse scripts. I'll use Getfield ( Get (ScriptParamter)) to get the contents of the field and Set field By Name [Get (ScriptParameter)]; <calculated value>] to adjust the contents of the field. In this case, the only thing I have to modify are the parameters for the button/trigger/whatever.
I hope that helps!
Thanks very much for your response. Great food for thought that really got me thinking. I will definitely be using your tip. In the mean time, it made me realize that I could create a custom function of "CustomFunction ( value )", and use it in conditional formatting as "CustomFunction ( Self )". Worked great.