Hi tkamiya,
I'm not certain how strongly the MG FB Warmtone takes colour in selenium. One way to achieve split-toning is to use two-bath sepia toner first. Dilute the bleach to 1/10th of the recommended strength, immerse the print and pull it out when the highlights start bleaching. Wash off the bleach then tone the print in your chosen toner - a variable one might be the best way to get your warm brown-yellow tone. After sepia toning, wash the print and tone in selenium.
If you work it the other way around, selenium then sepia, you have to watch the print carefully in selenium as it changes rapidly, and with some papers the change isn't obvious. If the print tones completely without you noticing, the sepia toner won't work. Sepia toned prints will change colour in the selenium, so you might want to practice using test prints. I don't know about thiocabamide toners, but sulphide tones tend towards pink when put through selenium toners.
Ilford MGIV FB takes a very slight blueish tone in selenium, so if the Warmtone does go the unwanted plum-colour, MGIV might be worth trying. The downside is that with MGIV it's very difficult to spot the colour change, so sepia toning first is a bit easier.
Good luck,
cheers,
kevs