There are 2 ways that i know of:
From the sequencer, click in the text field... Then HOLD DOWN the ALT key and quickly enter the 4-didit code for your character. So if you want Á‰ then enter ALT+0201
You can get ascii codes from the internet
OR, you can open Character Map program from windows, find your character then press SELECT then press COPY. Then go back to xpression and PASTE in your text field. Your accented character will be pasted into your text field. The good thing about the Character Map program is that when YOU select an accented character it will show you the keystroke code for that accent ALT+XXXX in the bottom right of the program.
Hope this helps.
S.
#XPression