So, I want to give my good-aligned human Telepath Psion a Mindsight, for which I need to give him a Telepathy special quality first, but the Mind's Eye (and every other non-printed-rules-source) was banned from use in our game. Are there any meanings of achieving that Telrepathy ability without giving up the alignment or getting into a horrid cascade of multiple classes/prestige classes?
The Shedu Crown soulmeld (Magic of Incarnum) grants the ability to "communicate telepathically" when bound to the Crown chakra.
Potential problem: The name of the ability is not "Telepathy", as soulmeld-granted abilities do not have specific names. Regardless, the reader will see that this is precisely the ability described by under Telepathy.
This can be accessed by either using two feats (Shape Soulmeld and Open Least Chakra) or a two-level dip in the Incarnate class. Too bad that the Mind's Eye is not allowed, as the Soul Manifester prestige class can be made quite useful. Still, there is some synergy between meldshaping and psionics through feats such as Midnight Augmentation.
Note: The Soulspeaker Circlet bound to the Throat chakra grants the same ability, but with a shorter range unless significant amounts of essentia are invested. It is less suitable for dips and/or dabbling.
Take one level of Mindbender (Complete Arcane PrC), if adaptation authorized - gives you telepathy 100 feet at level 1.
Take Psicrystal Affinity - you'll have a psicrystal that'll get feats - give him Mindsight - enjoy! (Your DM'll have to rule that psicrystal get feats, though... much debated...)
Convince your DM to let you become a Crystal Master (Mind's Eye Prc: Link) - and get the "Malachite embeded gem": "Malachite: The crystal master gains a limited telepathy. She can communicate telepathically with any creatures that speak a language that she speaks, provided they are within 30 feet. This range increases by 10 feet for each additional imbedded gem. She can address multiple creatures at once telepathically, although maintaining a telepathic conversation with more than one creature at a time is just as difficult as simultaneously speaking and listening to multiple people at the same time."