How to insert special character in sgm file and interprete it without isoents while opening in FM9.0

I have an sgm file which contains special characters in different languages.

<!DOCTYPE MANUAL PUBLIC "-//SWE-XXX//DTD XXX MANUAL-DTD 2.0//EN">
<MANUAL LANG="CS">
<TITEL>
Polish characters: &oacute;&ecirc;&iquest;&ntilde;&aelig;&Ntilde;&AElig;&Ecirc;&yen;&Oac ute;&pound;
Czech characters: &eacute;&igrave;&oacute;&iuml;&aacute;&oslash;&egrave;&iacute;&ugrave ;&ograve;&uacute;&Ograve;&Igrave;&Eacute;&Oacute;&Uacute;&Ugrave;&Egra ve;&Oslash;&Iacute;&Aacute;&Iuml; aacute: &aacute;</TITEL>
</MANUAL>

Is there any way to insert special character directly in sgm file, so that it won't have to be interpreted by isoents mapping rules?

isoent.rwr interpretes oacute as:

entity "oacute" is fm char 0x00F3;

But I would like to use 0x00F3 directly in fm file, so that if any additional character is needed - I won't have to update isoent files

I've tested already:

&#x00F3;

&x00F3;

&0x00F3;

but with no luck

Is there anyone who could help me with it?

I will really appreciate your help

/Joanna