I'm going to assume you know what you are doing - the following procedure is hazardous. I have however done this on a 1 g scale with no mishaps. You can use literature to fill in the gaps. Take your used Pt catalyst, and dissolve it up by heating it in aqua regia (it takes a while to dissolve). Evaporate the solution, and convert the resulting chloroplatic acid H2PtCl6 to ammonium chloroplatinate, (NH4)2PtCl6.
This next bit is in the Org. Synth. prep for the Adams catalyst. Mix 1 part ammonium chloroplatinate with 10 parts AR sodium nitrate by weight in a porcelain crucible, and heat slowly in a full bunsen flame (fumehood), the sodium nitrate will fuse (~350 deg C), and release copious NOx fumes. Once the fusion has occurred, heat the mass at full flame for 20 minutes - ideally reaching 500-550 deg C (i have no idea how you would measure this kind of temperature, i just heated as hot as it will go). Cool to room temperature, smash the mass up, and add to water, stirring well. Filter off the fine brown solid (PtO2.xH2O), wash well with water, dry in a dessicator and then its ready to go.