Allowing additional deeplinks in esyndicat is done easily from the admin panel and a small edit of 1 file:

For each additional listing you want to add, do the following:

In “Manage Listing Fields” add two custom fields with the following attributes.

Field1
**************************

Name: title1 
English Title: TITLE 1
Show On Pages: (checked) Suggest Listing
                       (unchecked) Listing Details 
Required Field: No 
Visible for admin only: No 
Field Type: Text
Field Length: 150
Field Default Value:

Field2
**************************

Name: url1 
English Title: URL 1
Show On Pages: (checked) Suggest Listing 
                       (unchecked) Listing Details 
Required Field: No 
Visible for admin only: No 
Field Type: Text
Field Length: 150
Field Default Value:

Edit Template:
******************
To display the additional link in the details page open view-link.tpl

Right after 

{foreach from=$fields item=field}
other code .........
{/foreach}

Add the following

{if $link.title1}
<tr>
<td>&nbsp;</td><td><a href="{$link.url1}">
{$link.title1}</a></td>
</tr>
{/if}

That’s it!
Of course you can do the same to add more additional links.

All this applies to the PRO version, I don’t know about the free one.

To see a demo, rakCha web directory