[TxMt] How to use "Find in Project" functionality in a command (help appreciated)

[Bert Fitié]

1. I'm a happy (64-year old, retired) enduser of textmate, not a  
programmer.
2. I'm using a textmate project as my "personal textbase". The  
project has many markdown files. I don't use markdown as a source to  
convert to html but as the real thing, as my final product (with an  
occasional preview for reading convenience).
3. My markdown file is a container for one or more articles, each  
about a separate topic. Every article is uniquely identified by a tag  
in the form of a string "tagid=<tagid>".
4. I'm using crossreferences to other articles in the form of a  
string "tagref=<tagid>".
5. To link from a tagref to the associated unique tagid I use the  
"Find in Project" dialog. I type "tagid=<tagid>" and click the single  
link in the result to load the relevant file.
6. I love to have the following command: with the caret in a  
"tagref=<tagid>" reference and pushing the enter key, the relevant  
file automatically loads.
7. I have no idea how to make this command; help is appreciated.