Membership Form Number of Installments

Danny Reader 2

In the BBNC membership form, the 'number of installments' field allows the end user to select way too many installments, up to 999.  There doesn't seem to be a way in settings to restrict this number.  I did find relevant BB cases that indicate this can be changed in the HTML code:
https://www.kb.blackbaud.com/articles/Article/103495
https://www.kb.blackbaud.com/articles/Article/47456


Before I ask my web design to have a look, does anyone have experience changing this field in code?  Any tips I can pass along to him would be greatly appreciated!  Thanks!