Dear All,
One cannot rely on browsers displaying the access key assignments (at present
or in the near future). To clarify the situation, consider the following
example given in the HTML 4.0 specification:
<LABEL for="fuser" accesskey="U">
User Name <INPUT type="text" name="user" id="fuser"> </LABEL>
On your current browser, this looks like the following:

User Name

The specification seems to suggest that a browser should automatically indicate
to the user that "U" is an accesskey for the input field, e.g. by underlining
that character (assumably as it appears within the LABEL element). But although
IE supports (from version 4.0 onwards) ACCESSKEY, there's no underlining
in the presentation. In fact there is no evidence of real support to LABEL.
It is also debatable whether the specification really suggests what it seems
to be suggesting--that browsers should, in a case like this, check the content
of the LABEL field and underline (any?) occurrence of the accesskey character!

Thus it seems that the author should take care of the underlining or other
specific presentation, e.g. writing the content of LABEL in this case as

<U>U</U>ser Name
Such explicit presentational suggestions may become unnecessary in the future
if the browser support improves, of course. But for the time being, we need
to consider how to present them.
To let users benefit from access keys, you need to take care of displaying
the access key assignments.
The method used in the examples above--explicitly telling the access key
after an element, and additionally bolding the access key letter when applicable--is
somewhat naivistic but it can reasonably be expected to carry the message
to those who need it. The main problem with it would probably not be the
naivity but the fact that a reference to access keys might confuse people
who do not need that information. They might have difficulties in understanding
whether "accesskey" is something they need to know about. You might consider
making that word a link to a suitable document about access keys. (The present
document of mine can be used for the purpose, although it would probably
be all too detailed for that.)
For normal submit (or reset) buttons in forms, underlining and bolding are
impossible, since the text in a button is specified using an attribute, and
attribute values cannot contain HTML markup. Thus, for example, if you have

then you cannot underline or bold the letter "A" in "Add this". Theoretically,
you could use INPUT TYPE="IMAGE" and an image which contains the text "Add
this" with A underlined (and/or bolded), but in practice image buttons cause
more problems than they might solve. Since the use of uppercase alone is
not a very good signal--even if you otherwise use all lowercase in submit
button texts--it seems to be necessary to include an explicit remark about
the access key.

Does anyone know how to do it on a Submit button? will be a miracle
and quite a challenge I guess...:-)

Thanks & Regards