If I remember well, computers from that time, from big name brands, like Gateway, IBM, Compaq, HP, etc, had very specific systems, including sometimes tailor made motherboards with custom BIOS, etc, and in all likelihood it does not have any overclocking features.
I may be wrong, but there is nothing like googling your computer model and see if anything comes up.
Like it was said before, you can still make a useful PC out of it tough. Using Linux for example, or, if it is fast enough (PII running at 400Mhz or 450Mhz), you can even try Windows XP. In either case, you should make sure you have 512MB of RAM. Anything below will make even Linux slow (unless you install one of those distros that have almost nothing in them).