SuperCard 3.0 allows the use of chunk expressions to get and set text attributes. For example:
get the textStyle of word 3 of field 1
if it is "bold" then
set the textStyle of word 3 of fld 1 to "bold,italic"
For earlier version of SuperCard, the program only allows you to set font attributes by first selecting the desired range of text, and then setting the text attributes of the field, which will affect only the selection.
For example, to change the third word to Palatino bold, you could script:
select word 3 of cd fld "TestField"
set the textFont of cd fld "TestField" to Palatino
set the textStyle of cd fld "TestField" to bold