You'll have to use Javascript and some regexp here because both first name and last name are placed in the same tag.
SET !EXTRACT_TEST_POPUP NO
TAG POS=1 TYPE=H3 ATTR=TXT:*<SP> EXTRACT=TXT
SET VAR1 eval("\"{{!EXTRACT}}\".match(/^\\s*\\S+/)[0]")
SET VAR2 eval("\"{{!EXTRACT}}\".match(/^\\s*\\S+\\s+(.+)\\s*$/)[1]")
PROMPT "VAR1={{VAR1}}, VAR2={{VAR2}}"