Hi Denis,
There's no built-in support for this. If you're comfortable with
scripting the simplest thing to do is probably to use a Perl (or
similar) script on the file exported from the COBOL system to convert
the numbers to a string representation of the decimal number, which can
be imported into a numeric field in Access.
Alternatively they can be imported to a text field in Access after which
it's possible to write a custom VBA function in an update query to
decode them and put the results into a numeric field.
Otherwise, look into software such as TextPipe Pro and Monarch. A
standard installation of TextPipe Pro won't handle these fields, but the
company seems very willing to create custom filters.