In addition to visualizing Manjushri, it is recommended that the querent recite his mantra: OM AH RA PA TSA NA DHI (either 3 or 7 times). There are further rituals (and a lot of other information) that you may learn about in the book Mo: Tibetan Divination System by Jamgon Mipham (translated by Jay Goldberg).
The 6 last syllables of the mantra above are on the 6 sides of the traditional Mo die, but we can use regular dice by adapting the dice like this:
| AH |
= |
6 |
| RA |
= |
2 |
| PA |
= |
3 |
| TSA |
= |
5 |
| NA |
= |
4 |
| DHI |
= |
1 |
|