The patch allows a-a-m-c to work for list of values in single word (e.g. 
as used by _values). This looks pretty straightforward and apparently 
does not have any side effects; comments?

Index: Completion/Base/Utility/_values
===================================================================
RCS file: /cvsroot/zsh/zsh/Completion/Base/Utility/_values,v
retrieving revision 1.9
diff -u -p -r1.9 _values
--- Completion/Base/Utility/_values	27 Feb 2007 20:44:01 -0000	1.9
+++ Completion/Base/Utility/_values	9 Jan 2009 17:44:46 -0000
@@ -12,6 +12,8 @@ if compvalues -i "$@"; then
   local noargs args opts descr action expl sep argsep subc test='*'
   local oldcontext="$curcontext"
 
+  compstate[list_in_word]=1
+
   compvalues -S argsep
   compvalues -s sep && [[ -n "$sep" ]] && test="[^${(q)sep}]#"
 
Index: Doc/Zsh/compwid.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/compwid.yo,v
retrieving revision 1.45
diff -u -p -r1.45 compwid.yo
--- Doc/Zsh/compwid.yo	18 Oct 2008 19:16:24 -0000	1.45
+++ Doc/Zsh/compwid.yo	9 Jan 2009 17:44:47 -0000
@@ -285,6 +285,13 @@ tt(messages) both kinds of explanation s
 will be set appropriately on entry to a completion widget and may be
 changed there.
 )
+vindex(list_in_word, compstate)
+item(tt(list_in_word))(
+This controls how accept-and-menu-complete widget handles suffix. If
+set to tt(0) (default), suffix will be removed and replaced by space.
+If set to tt(1), suffix is preserved so next match will be inserted
+in the same word.
+)
 vindex(list_lines, compstate)
 item(tt(list_lines))(
 This gives the number of lines that are needed to display the full
Index: Src/Zle/compcore.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/Zle/compcore.c,v
retrieving revision 1.98
diff -u -p -r1.98 compcore.c
--- Src/Zle/compcore.c	26 Sep 2008 09:11:30 -0000	1.98
+++ Src/Zle/compcore.c	9 Jan 2009 17:44:47 -0000
@@ -325,6 +325,7 @@ do_completion(UNUSED(Hookdef dummy), Com
     comppatinsert = ztrdup("menu");
     forcelist = 0;
     haspattern = 0;
+    complistinword = 0;
     complistmax = getiparam("LISTMAX");
     zsfree(complastprompt);
     complastprompt = ztrdup(((isset(ALWAYSLASTPROMPT) && zmult == 1) ||
Index: Src/Zle/complete.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/Zle/complete.c,v
retrieving revision 1.44
diff -u -p -r1.44 complete.c
--- Src/Zle/complete.c	15 Nov 2008 21:27:46 -0000	1.44
+++ Src/Zle/complete.c	9 Jan 2009 17:44:47 -0000
@@ -38,6 +38,7 @@ zlong compcurrent,
       complistmax;
 /**/
 zlong complistlines,
+      complistinword,
       compignored;
 
 /**/
@@ -1146,6 +1147,7 @@ static struct compparam compkparams[] = 
       GSU(unambig_pos_gsu) },
     { "insert_positions", PM_SCALAR | PM_READONLY, NULL,
       GSU(insert_pos_gsu) },
+    { "list_in_word", PM_INTEGER, VAL(complistinword), NULL },
     { "list_max", PM_INTEGER, VAL(complistmax), NULL },
     { "last_prompt", PM_SCALAR, VAL(complastprompt), NULL },
     { "to_end", PM_SCALAR, VAL(comptoend), NULL },
@@ -1596,7 +1598,7 @@ setup_(UNUSED(Module m))
 	compvared = compqstack = NULL;
     complastprefix = ztrdup("");
     complastsuffix = ztrdup("");
-    complistmax = 0;
+    complistmax = complistinword = 0;
     hascompmod = 1;
 
     return 0;
Index: Src/Zle/compresult.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/Zle/compresult.c,v
retrieving revision 1.75
diff -u -p -r1.75 compresult.c
--- Src/Zle/compresult.c	7 May 2008 08:53:40 -0000	1.75
+++ Src/Zle/compresult.c	9 Jan 2009 17:44:48 -0000
@@ -1309,21 +1309,23 @@ accept_last(void)
 	lastbrbeg->str[l] = ',';
 	lastbrbeg->str[l + 1] = '\0';
     } else {
-	int l;
-
 	zlemetacs = minfo.pos + minfo.len + minfo.insc;
-	iremovesuffix(' ', 1);
-	l = zlemetacs;
-	zlemetacs = minfo.pos + minfo.len + minfo.insc - (*(minfo.cur))->qisl;
-	if (zlemetacs < l)
-	    foredel(l - zlemetacs, CUT_RAW);
-	else if (zlemetacs > zlemetall)
-	    zlemetacs = zlemetall;
-	inststrlen(" ", 1, 1);
+	if (!complistinword) {
+	    int l;
+
+	    iremovesuffix(' ', 1);
+	    l = zlemetacs;
+	    zlemetacs = minfo.pos + minfo.len + minfo.insc - (*(minfo.cur))-
>qisl;
+	    if (zlemetacs < l)
+		foredel(l - zlemetacs, CUT_RAW);
+	    else if (zlemetacs > zlemetall)
+		zlemetacs = zlemetall;
+	    inststrlen(" ", 1, 1);
+	}
 	minfo.insc = minfo.len = 0;
 	minfo.pos = zlemetacs;
 	minfo.we = 1;
-    }
+	}
 
     if (!wasmeta)
 	unmetafy_line();