The problem is multifold.

1. You need to determine if the original emulsion is sensitive to other than blue.
2. If 1 = yes, then sensitize to the region(s) left out of #1. Hope that the new dye(s) do not remove existing dyes if any.
3. If 1 = no, then you need to get the proper pan dye to add and just add it with no worry.
4. Make sure you work in total darkness or IR.
5. Before you do anything, find a source for the dye.

Now, how to do 2 or 3. Dissolve the dye in an appropriate solvent for the dye. This will usually be at the rate of 100 mg - 1 gram / 100 grams of solution. This is then normally added at about 50 - 100 mg of dye / mole of Silver to the melted emulsion and held for 15 minutes with stirring before coating. All should be normal from this point on.

If the coating is already made, you will have to work entirely by trial and error to bathe the emulsion in dye solution to give the right sensitization. You should wash briefly after the soak in dye solution. This method is the least desired.

During this all, remember that the emulsion starts out with zero added sensitivity, increases speed in the desired region of the spectrum as dye level is increased, and then as you go up from there, both peak and blue sensitivity will decrease and development rate will decrease. Dyes are desensitizers and retarding agents at high levels.