Specify relative path to current core conf folder when it's originally relative to solr home

[scott.chu]

I got a custom tokenizer. When configuring it, there's an attribute 'fileDir', 
whose value is  a path relative to solr home. But I wish it can be relative to 
current core. Is there some system variable out-of-box, say {current_core}, 
that I can use in the value? For example, 

solr home = /solr5/server/solr
In the current core's solrconfig.xml, I can specify
    <requestHandler name="/custom_tokenizer" class="...." >
        <lst name="defaults">
            <str name="fileDir">myfiledir</str>
        </lst>
    </requestHandler>

so it will refer to /solr5/server/solr/myfiledir.

But I wanna put myfileDir under current core's conf folder. I wish there's 
something such as:
...
            <str name="fileDir">{current_core}/conf/myfiledir</str>
...

Is it possible?