T_c^{/Symbol \245}
But, that leaves an ugly space between the symbol and superscript. You can force alignment with an @ character:
T@_c^{/Symbol \245}This works fine for standard characters, but for slanted variables, the align character makes the superscript overlap. To fix this we insert a partial before the infty symbol in the superscript. To do this we combine two text effects, blank characters &{a} and font size scaling {/* }:
T@_c^{{/*0.5 &{c}}{/Symbol \245}}
To give the desired result. You can change the factor 0.5 to whatever you need, with 1.0 being full character width.