You can access a skill as you do it in singleplayer:
But if you want that the skill has the same value on all pcs, you have to use enet_send_skill() if you change the value of the skill (=> send the new value to all other participants).
Please note that the entity has to be a global entity (created with enet_ent_create()) otherwise enet_send_skill() won't work.
Read the ANet manual entries enet_send_skill() and enet_ent_create() for more details.
Best regards,
Peter Soxberger