Move the cursor to the position where the character is to be inserted. Use Tools, Symbol Map on the menu to display the symbol map. Double-click on the desired character to insert it.
Use Tools, Modify Symbols on the menu (or right-click and select Modify Symbols from the pop-up menu) to display the Modify Symbol map. This has an edit box into which special characters can be inserted (e.g. by running the Windows Character Map application). These characters can then be transferred to the symbol map.