I want to draw a box around formulae I am inserting into a page in Pages using latex.
Pages will not accept formulae inside text boxes and this would be a lame method anyway.
Here is a option for drawing a box around formulae inserted into a Pages document. This is not super elegant but could be what the OP is looking for.
From the Menu select Insert > Equation... Enter the desired LaTex or MathML into the dialog box.
Insert a 'box'. Generally, a square shape sized, fill color removed or set to desired color, with a border of the desired width.
Align both so that the equation appears in the center.
More info on LaTex or MathML for Pages: Pages version 7.1 (5683) inserting equations using LaTex or MathML.