Hi,
this is part of my XML:

<xml>
     <rowset:data>
        <target:row attr1='1' attr2='900' attr3='ABC' attr4='TREE-JOKER-BASEBALL-' />
     </rowset:data>
</xml>

In XSLT 1.0 need to create a regex to match values into attr4, so I need something "Perl" like attr4 =~/TREE|JOKER/

This is my query:
/xml/rowset:data/target:row[(@attr4 = '/TREE|JOKER/')] but doesn't work.

XSLT 1.0 doesn't use regular expressions (why do you think it does?)
You have to decompose your requirement into available XPath functions,
in your case
 /xml/rowset:data/target:row[contains(@attr4,'TREE') or
   contains(@attr4,'JOKER']
should do the trick.