If I have a read-only field in a disconnected recordset, how can I make it not read-only?

I don't want to update the data source (As I know I can't) but I want to update the field in the recordset nether the less.

When I try, I get RT error -2147217887: "Multiple step operation generated errors. Check each status value"

The field status = 11 (adFieldSchemaViolation).

Any ideas anyone?