If it's checkout conversions that you're looking to track, I think you'll need to get a developer involved as the pixel will change depending on the basket/order so that information on the specific order can be sent through.
If you're comfortable installing an extension it seems like there are a few on Magento 1 that could help you looking at the Marketplace: https://marketplace.magento.com/catalogsearch/result/?q=facebook%20pixel#q=facebook%20pixel&idx=m2_c...
On the other hand, if it is static piece of javascript, i.e. it doesn't need to change on each page and still needs to go on a specific page then one work around would be to create a new static block and put the javascript in it. Save that, and then go to CMS Widgets. This functionality in magento allows you to place specific widgets in specific locations on specific pages which can be very useful. One type of widget gives you the option of selecting a static block. So you could use the widget to select your new static block. Some information on widgets available here: http://docs.magento.com/m1/ce/user_guide/cms/widget-create.html
Hope that helps.
----
If you've found one of my answers useful, please give "Kudos" or "Accept as Solution" as appropriate. Thanks!